Venomous Animals - L

Lachesis acrochorda
Lachesis melanocephala
Lachesis muta
Lachesis stenophrys
Lapemis curtus
Lapemis hardwickii
Laticauda colubrina
Laticauda laticaudata
Laticauda semifasciata
Laticauda spp.
Latrodectus curacaviensis
Latrodectus geometricus
Latrodectus hasselti
Latrodectus hesperus
Latrodectus indistinctus
Latrodectus mactans
Latrodectus spp.
Latrodectus tredecimguttatus
Latrodectus variolus
Leiurus quinquestriatus
Leiurus spp.
Leptomicrurus collaris
Leptomicrurus narduccii
Leptomicrurus renjifoi
Leptomicrurus scutiventris
Lonomia achelous
Lonomia obliqua
Lonomia spp.
Loxosceles deserta
Loxosceles gaucho
Loxosceles intermedia
Loxosceles laeta
Loxosceles reclusa
Loxosceles rufescens
Loxosceles spp.

Lachesis acrochorda

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Identification

Family: Viperidae

Scientific Names: Bothrops arachorda, B. verrugosa, Lachesis calcaratus, L. muta (in part)

Common Names: Chocoan Bushmaster, verrugosa, diamante, mapana rayo, martiguaja, montuno, pudridora, verrugosa del Choco, guacama

Description

Very large, relatively slender, big-headed terrestrial pitviper, adults usually 1.8-2.3 m long (max. 3+ m); w/ pronounced mid-dorsal ridge (esp. front 1/4 of body), head lanceolate, reddish or brown w/ dark spots, snout not elevated; body yellowish-brown to reddish-tan w/ 23-31 dark dorsal rhombs, 31-39 (usually 35) midbody dorsal scale rows, belly white or cream w/ small darker blotches along sides.

Habitat

Found mainly in tropical wet & moist forests w/ rainfall of 2.5-6.0 m/year; found on both Atlantic & pacific slopes of eastern Panama & western Columbia, then south along the pacific slope into northwestern Ecuador. Lives from near sea level to about 1,600 m elevation, most records are from 500-1,000 m elevation.

Activity and Behavior

Mainly nocturnal, inactive during day, generally nonaggressive, but males often active & engage in ritual combat in the daytime during mating season; Usually hide under logs, in rodent burrows or rock crevices. Feed mainly on small mammals or birds. Oviparous, females often remain coiled around or on their clutch (often up to 10 eggs).

Venom Characteristics

Venom includes factors that are proteolytic, hemorrhagic, myotoxic, clotting inhibitors & possibly neurotoxic. The sheer volume which can potentially be injected in one bite make these snakes (esp. adults) very dangerous. All 4 currently recognized Lachesis species combined probably cause >100 human deaths/ year in Central & South America.

 

Lachesis melanocephala

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Identification

Family: Viperidae

Scientific Names: Crotalus mutus, Lachesis muta melanocephala, Lachesis mutus

Common Names: Black-headed bushmaster, cascabel muda, matabuey, plato negro

Description

Large, fairly slender, terrestrial, big-headed pitviper, adults usually 1.9-2.0 m long (max. 2.4 m); top of head all black, body yellow, yellowish-tan, creamy-tan or reddish-tan, w/ 26-33 dark diamond-shaped dorsal blotches, edged w/ a darker line, a series of cream to yellow-tan vertebral spots are interspersed between the dark blotches; 36-41 midbody dorsal scale rows, belly white or cream colored.

Habitat

Found mainly in tropical moist forest, wet forest, & premontane wet forest which receive 2.5-4.5 m of rain/year, usually at 500 m elevation, or higher. Limited to Pacific slopes of southern Costa Rica (possibly also occurs in adjacent areas of Panama, but no verified specimens from there, so far).

Activity and Behavior

Very similar in biology & behavior to other closely-related species. For more probable typical behavior details (i.e., based on a closely-related species), See Lachesis muta.

Venom Characteristics

Similar to some closely-related species. See Lachesis muta.

 

Lachesis muta

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Identification

Family: Viperidae

Scientific Names: Bothrops surucucu, Coluber alecto, C. crotalinus, Cophius crotalinus, Crasedocephalus crotalinus, Crotalus mutus, Lachesis ater, Lachesis muta muta, L. m. rhombeata, L. m. noctivaga, L. mutus, L. rhombeata, Lachopesis rhumbeata, Scytale ammodytes, S. catenata, S. catenatus, Trigonocephalus ammodytes, T. brasiliensis, T. crotalinus, T. rhumbeatus

Common Names: Bushmaster, South American Bushmaster, cascabela muda, cascabel pua, cuanira, diamonte, shuchupe, matabuey, mapepire, parariapu, surucucu, urukuku, verrugosa [PLUS more than 50 additional local common names]

Description

Very large, rather slender, big-headed terrestrial pitviper, adults usually 2.0-3.0 m long (max. 3.6+ m); longest poisonous snake in the Americas. Prominent mid-dorsal ridge, esp. on the front 1/2 of body. Body reddish-brown, yellowish-tan, or pinkish-tan, w/ dark brown or black diamond-shaped dorsal blotches (often edged w/yellow or cream). Belly white or ivory, head lanceolate; tan, brown or reddish-brown w/ dark postocular stripe, & dark speckling/ spots.

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Habitat

Mainly found in tropical rainforests & lower montane wet forests that get 2.0-4.0 m annual rainfall; may occur along rivers in drier regions. Often found near large, buttressed trees or fallen logs, from near sea level up to 1,000 m elevation.

Activity and Behavior

Mainly terrestrial & nocturnal, most likely to respond quickly to disturbance near dawn (often inflating neck & vibrating tail rapidly). The southeastern Costa Rican population reportedly is highly aggressive when disturbed. Oviparous, w/ 5-18 eggs/ clutch. Prey mainly on small mammals. Large adult captive specimens reportedly occasionally emit a long "whistling" sound.

Venom Characteristics

Has potent proteolysins; envenomation causes intense pain, swelling, & necrosis (often extensive) at the bite site, sometimes followed by gangrene. Bites from this species in Panama & Atlantic lowlands of Costa Rica have historically had a high case fatality rate.

Lachesis stenophrys

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Identification

Family: Viperidae

Scientific Names: Bothrops acrocordus, Lachesis acrocorda (in part), L. muta stenophrys

Common Names: Central American Bushmaster, bushmaster, boccaraca de javillo, cascabel muda, cascabela muda, ija, mapana, matabuey, mazacuata, toboa real, verrugosa

Description

Very large, rather slender, big-headed terrestrial pitviper, adults usually 2.0-2.5 m long (max. 3.48 m); pronounced mid-dorsal ridge (esp. on front 1/4 of body), head lanceolate, reddish-tan or brown, sometimes w/ sparse black speckling; body grayish-yellow, dull tan, yellowish-tan, or reddish-brown, w/ 23-29 dorsal rhombs w/ darker edges, 33-38 (usually 35) midbody dorsal scale rows, belly white or cream w/ irregular dark clumps or mottling on posterior 1/4 of body.

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Habitat

Found mainly in tropical rainforest & lower montane wet forest w/ rainfall of 2.0-4.0 m/year, also along streams in drier sites, usually on steep hillsides, of primary forest, sheltering under fallen trees; in the Atlantic lowlands from sea level to about 1,000 m elevation in Nicaragua, Costa Rica & Panama.

Activity and Behavior

Mainly nocturnal, mainly terrestrial, generally not aggressive (males are irritable & engage in ritual combat in daytime during mating season). Usually hide under fallen trees in daytime, prey mainly on small mammals (sometimes birds), oviparous (clutch size not reported).

Venom Characteristics

Highly potent proteolytic, hemorrhagic, myotoxic, clotting & possibly even neurotoxic factors present. Human envenomations fairly frequent, often quickly fatal; symptoms of even limited envenomation (by even young specimens) often include immediate pain, rapidly progressive swelling & numbness, rapid pulse, shock, vomiting, diarrhea, stabbing muscle pains, & respiratory distress.

Lapemis curtus

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Identification

Family: Hydrophiidae

Scientific Names: Enhydris curtus, Hydrophis abbreviatus, H. brevis, H. fayreriana, H. hardwickei, H. pelamidoides, H. p. annulata, H. pelamoides, H. propinquus, Hydrus curtus, Lapemis loreatus

Common Names: Shaw's sea snake, short sea snake

Description

Large, powerfully built sea snake, w/ short tail, broad head, adults usually 0.8-1.1 m long (max. 1.5 m); body scales hexagonal, scales on belly & chin keeled or tuberculate in males, relatively large mouth. Body usually tan w/ dorsal olive crossbands which sometimes look almost diamond-shaped from above, belly pale yellowish or cream.

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Habitat

Found mainly in marine water varying from clear (above coral reefs) to silty shorelines & turbid estuaries; in near-shore marine waters of Persian Gulf, & northern Indian & southwestern Pacific Oceans (to Taiwan).

Activity and Behavior

Both diurnal & nocturnal, stays in marine water, feeds on a variety of fish, crustaceans & squid; ovoviviparous, w/ usually 1-15 young/ litter.

Venom Characteristics

Potent venom, w/ neurotoxic & myotoxic factors; causes renal failure. Relatively few humans bitten, but has caused human fatalities.

 

Lapemis hardwickii

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Identification

Family: Hydrophiidae

Scientific Names: Enhydris hardwickii, Hydrophis hardwickei, H. hardwickii, Hypsirhina hardwickii, Lapemis curtus hardwickii

Common Names: Hardwicke's spine-bellied sea snake, short sea snake

Description

Medium-to-large, stout, short, large-headed sea snake, adults usually 50-70 cm long (max. 86 cm); keeled or tuberculate scales along belly & chin, body usually pale olive to tan, w/ darker olive to dark-gray dorsal crossbands (sometimes encircling body), belly whitish, sometimes whole body is drab olive above w/ no obvious patterning, head pale olive to black on top. Tail laterally flattened & "oarlike."

Habitat

Range limited to Australia-Asian region; swims only in marine waters & eats various available fish, crustaceans & squid over marine near-shore reef & silted seabeds.

Activity and Behavior

Very similar to L. curtus in activity & general biology. Very aggressive, tries to bite without provocation. For details of closest related species, See Lapemis curtus.

Venom Characteristics

Not well known. For details about a closely-related species, See Lapemis curtus.

Laticauda colubrina

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Identification

Family: Hydrophiidae

Scientific Names: Anguis platura, Coluber laticaudatus, C. platycaudatus, Hydrophis colubrina, Hydrus colubrinus, Laticauda scutata, Platurus colubrinus, P. fasciatus, P. frontalis, P. laticaudatus (in part)

Common Names: Yellow-lipped sea krait, Nattern-Plattschwanz

Description

Rather large, fairly thick-bodied seakrait, adults usually 90-120 cm long (max. about 140 cm); body bluish-gray w/ black crossbands which often encircle whole body; belly whitish to cream (w/ expanded scales or scutes), front of head w/ a broad cream or whitish band (from one eye around to the other) which includes both lips. Tail "oarlike."

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Habitat

Mainly found in marine waters & (sometimes) on adjacent land along nearby coasts, mainly in the regions of the eastern Indian & southwestern Pacific Oceans.

Activity and Behavior

Very docile, seldom ever attempts to bite even when handled. Feeds almost exclusively on eels (e.g., moray, zebra & conger eels). Very agile while crawling over land (usually at night), for considerable distances. Hunt prey in marine waters, come ashore (or onto rocks & pilings) to mate, lay eggs, digest meals & drink fresh water. Oviparous, usually 4-20 eggs/ clutch.

Venom Characteristics

Mainly neurotoxic w/ myotoxic factor(s). Produce & inject a rather small volume of venom in a given bite. Bites of humans are rare but a few have been reported. No significant human envenomations or fatalities documented, so far.

 

Laticauda laticaudata

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Identification

Family: Hydrophiidae

Scientific Names: Coluber laticaudatus, Laticauda laticaudata affinis, L. l. laticaudata, L. l. wolffi, L. scutata, L. wolffi, Platurus affinis, P. fischeri, P. laticaudatus, P. laurenti, P. muelleri,

Common Names: Common seakrait, blue-lipped seakrait, brown-lipped seakrait

Description

Medium-to-large fairly thick-bodied seakrait, adults usually 90-110 cm long (max. 120+ cm); body deep blue to light blue dorsally, w/ wide black bands (usually completely encircling body), cream to whitish belly, upper lip (labial scales) usually dark brown.

Habitat

Found in shallow marine waters & nearby lands in the Austral-asian region of the northeastern Indian & southwestern Pacific Oceans.

Activity and Behavior

Mainly feed on moray eels & elongate fish (like gobies) in their marine burrows, oviparous, mate, digest meals, & lay eggs on land (1-14/ clutch). Usually come onto land mainly at night.

Venom Characteristics

Mainly neurotoxins & myotoxins, may cause renal failure. No serious human bites or envenomations reported.

Laticauda semifasciata

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Identification

Family: Hydrophiidae

Scientific Names: Platurus fasciatus, P. f. var. semifasciata, P. semifasciata, Pseudolaticauda semifasciata

Common Names: Erabu seakrait, Chinese seasnake

Description

Large, blunt-nosed, stout-bodied seakraits, adults usually 0.8-1.5 m long (max. >2.0 m), body light blue-grayish & encircled w/ 35-40+ dark brownish-red bands, each widest at dorsal midline (more than twice as wide as on belly). Head mostly dark brownish-red above, lighter below. Belly w/ wider scales (scutes), tail "oarlike."

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Habitat

Mainly found in marine waters &/or on adjacent shores (land) from Indonesia to Japan. Often found in large numbers in rainy season, especially near or on rocky near-shore islands along east Asian coasts (Japan, China, etc.). Often caught in local fishermen's nets (several in each cast of a net), & skins are sold.

Activity and Behavior

For details of behavior & habits of a closely-related species, See Laticauda laticaudata.

Venom Characteristics

Mainly neurotoxic & myotoxic. Tests on lab animals have shown the main effect is respiratory disfunction. Amount of venom available for injection by large individuals at each bite (17+ mg) makes these potentially dangerous. Apparently seldom bite or envenomate humans, & no human fatalities documented, so far, from bites by this species.

Laticauda spp.

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Identification

Family: Hydrophiidae

Scientific Names: There are currently at least 8 recognized named species in the genus Laticauda, but only a few are commonly enough encountered by humans to be of concern or interest. Some species are limited to relatively small or remote ranges (L. schistorhynchus) or to a single land-locked brackish lake (e.g., L. cickeri).

Common Names: Seakraits (see individual listed species)

Description

Fairly large, cylindrical, fairly thick-bodied seakraits, w/ blunt rounded snouts; most of which are about 1.0-1.2 m long (some >1.5 m), usually w/ brightly colored bodies which are dark above, whitish below, & patterned w/ broad obvious dark bands (often encircling the body). Some have contrasting markings on their head or lips.

Habitat

Mainly found in moderately-shallow to shallow marine waters & adjacent land (often islands) along the margins of the northern Indian & western or southwestern Pacific Oceans.

Activity and Behavior

Most species hunt their prey in marine waters, then come onto dry land (shore, rocks, or pilings) to digest the meal, mate, & lay their eggs. Most species feed on various near-shore or reef marine fish or eels. Mainly come out of water only at night.

Venom Characteristics

Main venom factors are either neurotoxins or myotoxins, & although potentially deadly, reported bites & envenomations of humans by there snakes are rare.

 

Latrodectus curacaviensis

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Identification

Family: Theridiidae

Scientific Names:

Common Names: South American Black Widow, Arana del trigo, Brazilian Black Widow

Description

Medium-sized cobweb spider, adult females w/ body (= cephalothorax + abdomen) usually 11-17 mm long. Female's abdomen rather large, rounded like a grape; w/ several bright red irregular stripes & blotches covering >1/2 its surface. Body & legs dark brownish to black, "satiny" surface (not shiny). Males much smaller, thinner w/ relatively longer legs. Males & young usually w/ varying patterns of many reddish, white, &/or brown stripes & spots.

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Habitat

Usually found hanging in its cobweb type web in upper corners of outbuildings, under logs, in sheds, stone fireplaces, etc.; often near trash & debris. Wherever it is usually fairly dry, dark, & prey insects are adequate (i.e., not exposed to direct sun, rain, or general predators, like birds or lizards). Limited to South America. Probably also occurs in Argentina, Bolivia, Paraguay, & Peru, but no confirmed specimens from there so far.

Activity and Behavior

Mainly nocturnal, tries to avoid large animals & people; but female may aggressively defend her egg sac. Feed on wide range of available insects that are caught in its cobweb, which is usually about 1 ft. (30 cm) across (in 3-dimensions). Males may be eaten by females (usually after mating) if prey has been scarce, but this does not always happen.

Venom Characteristics

Mainly neurotoxic (presynaptic sites). Bite often hardly noticed until >15 min later, then intense local pain, often spreading, & other systemic effects like sweating, rapid breathing & heart beat, eyelids swelling, salivation, rigid & painful abdominal muscles, sometimes nausea, vomiting & impaired sight. Human fatalities occur (up to 5% in untreated cases), but are infrequent, & children are most severely affected.


 

Latrodectus geometricus

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Identification

Family: Theridiidae

Scientific Names: Latrodectus concinnus, L. obscurior, L. mactans (in part), L. m. tredecimguttatus, L. zickzack

Common Names: Brown widow, grey widow, brown button spider, geometric button spider, knoppie spider, knoppie

Description

Medium-sized cobweb spider, female's body (cephalothorax + abdomen) usually 7-14 mm long (male's body 3-5 mm long & much thinner). Female's globular abdomen usually w/ red-orange "hourglass" mark on ventral surface; dorsally tan to very dark-brown w/ prominent but variable-shaped black-&-white geometric pattern. Males & young variously patterned w/ black, white, & orange stripes & spots dorsally. Each agg sac is covered w/ small raised bump-like papules.

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Habitat

Found mainly hanging in its cobweb in an upper corner of a partly shaded, partly sheltered moderately humid site, like under eaves, in a basement corner, in wood piles, crawl space, or windows (often below projecting sill). Common in & around humans' homes, wherever adequate prey populations occur. Cosmopolitan, found essentially everywhere but the arctic & antarctic, & is one of the 2 most wide-spead of 31 currently named species in this genus. Probably is often moved in commerce.

Activity and Behavior

Mainly nocturnal. Usually hang in their web until some prey contacts it. Then the spider rushes to the spot, wraps the prey in more stands of silk, bites (envenomates) it, & waits a while before sucking out the prey's body juices. Hangs egg sacs in its coarse 3-D cobweb. Usually avoids big animals & people, but may aggressively defend egg sacs. Human envenomations (bites) occur when the spider is molested, brushed against, stepped on, or trapped in clothing being donned.

Venom Characteristics

Neurotoxic (at pre-synaptic sites), but less potent than that of many typical black-colored species in this genus. Effects of envenomation can include severe local pain, sweating, lacrymation, limited muscle spasms, breathing & heart difficulties. Deaths due to this species are cited in older literature, but no recent (e.g., in past 20 yrs.) well-documented case. Prior reported fatalities may have been due to other spp. (misidentified), or facilitated by other contributing medical problems.

 

Latrodectus hasselti

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Identification

Family: Theridiidae

Scientific Names: Latrodectus agoyangyang, L. ancorifer, L. dahli, L. elegans, L. hasselti aruensis, L. kapito, L. luzonicus, L. mactans hasselti, L. scelio, L. s. var. indica, Theridium malanogantha, T. zebrina

Common Names: Red-backed spider, Australian red-back, red-backed widow spider, stripe-backed spider, katipo, nin'lau, laba pantat merah

Description

Medium-sized cobweb spiders, females' body (cephalothorax + abdomen) usually 10-16 mm long, satiny jet-black, w/ a variable, but obvious, red stripe along the mid-dorsum of their spherical abdomen (from before the mid-point around to their posterior ventral spinerettes. Males rarely seen, usually about 3 mm long, slender, lighter colored usually brownish w/ reddish (sometimes yellowish) & white markings.

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Habitat

Mainly found in moderately dry, built up areas, often around buildings, outdoor furniture, machinery, & stacked material (e.g., firewood). Widespread in Australia, but also in several Southeast Asian countries & India & probably occurs in several other countries (e.g., Malaysia), but no confirmed specimens have been reported from them so far. Has probably been dispersed in commerce (e.g., the record from Saudi Arabia).

Activity and Behavior

Mainly nocturnal, usually build (& hangs in) undefined "cobweb type" webs under logs, ledges, large rocks, or in corners of open buildings. Prey on whatever (mainly insects) gets caught in their web. Not usually aggressive, but female will sometimes defend her egg sacs. Male not always eaten after mating, unless other prey is scarce, but he often dies soon afterward anyway.

Venom Characteristics

Mainly neurotoxic (at pre-synaptic sites). Pain from bite usually delayed up to 15 min. Envenomation can cause intense local & spreading pain, muscle twitching, sweating, lacrymation, breathing & heartbeat irregularities, salivation, nausea, vomiting, restlessness, fever, & general weakness. Fatalities have been documented, but have not caused a human death (in Australia) in the past several decades, partly due to availability of effective antivenom.

Latrodectus hesperus

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Identification

Family: Theridiidae

Scientific Names: Latrodectus mactans (in part)

Common Names: Western Black Widow, southwestern jockey spider, widow spider

Description

Medium-sized cobweb spider, female's body (cephalothorax + abdomen) usually 11-14 mm long, satiny dark brown to black w/ reddish "hourglass" mark on posterior ventral abdomen (the front part of hourglass distingtly longer & wider than back part). Female abdomen rounded & globular. Males much smaller, rather slender w/ relatively long legs. Males & young often w/ varying pattern of multiple stripes or blotches of red, white & brown on abdomen.

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Habitat

Usually found hanging in typical "cobweb," usually near ground level under various objects, often in small animal burrows, often near garbage or debris, wherever insect prey is abundant. Well adapted to semi-arid areas. Natural range mainly limited to southwestern U.S. Well adapted to semi-arid sites. (Kansas south to Texas, and westward) & northwestern Mexico. Has been reported from Israel (probably as an introduced species).

Activity and Behavior

Mainly nocturnal, hangs in web awaiting prey, usually tries to avoid large animals & people, but may aggressively defend egg sacs, which it hangs in its web. Preys on nearly any kind of arthropod or insect which gets caught in its web. Males not always eaten after mating w/ female, usually only if female has not fed recently, but he is often "biologically spent" & dies soon afterward anyway.

Venom Characteristics

Mainly neurotoxic (at presynaptic sites). Bite often not felt 'til several min. later, then pain may be locally intense. Severe envenomation can cause spreading intense pain, sweating, fast & shallow breathing, swollen or drooping eyelids, excess (or no)salivation, cardiac rhythm irregularities, & sight impairment. Human fatalities are rare & usually due to secondary complications or concurrent, but separate, additional medical problems.

 

Latrodectus indistinctus

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Identification

Family: Theridiidae

Scientific Names:

Common Names: Black Button Spider, Widow Spider, knoppie, knoppe-spinnekop

Description

Medium-sized cobweb spider, adult females' body (cephalothorax + abdomen) usually 7-16 mm long. Abdomen spherical, w/ dark-brown to black, satiny (silky) appearance. Abdomen variably patterned w/ white or red flecks or bands above (may be unmarked), many of which fade w/ each molt, often indistinct at maturity. Most retain at least short red stripes radiating up the dorsal abdomen tip, just above (& often also ventral to) the spinnerets. Males usually 2.5-5 mm long.

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Habitat

Mainly found in edges of tangled brush & uncut grass or tall vegetation in fairly dry sites, often at edges of agricultural areas or sparse forest, & often associated w/ a side of a ditch, trench or banked soil. Not common around buildings. Limited to southern Africa. May also occur in Lesotho, Swaziland, Botswana, Mozambique & Zimbabwe, but no specimens confirmed from those countries so far.

Activity and Behavior

Nocturnal, usually not aggressive; often drop to ground & "play dead" if disturbed. Hangs egg sacs in cobweb, which is usually built in brushy vegetation or debris, w/ prey available nearby. Prey mainly on insects or arthropods. Females will sometimes aggressively defend their egg sacs; many will bite if molested or their body or a foot/leg is pinched.

Venom Characteristics

Neurotoxic. Envenomation can cause slightly delayed (by a few minutes) sharp, burning pain at bite site (spreads to lymph nodes in about 15 min.); severe muscle pain & cramps within 1 hr.; anxiety, sweating, fever, slurred speach, nausea, & headaches. Fewer than 5% of human envenomations are fatal, usually due to respiratory failure, & mainly affect children.

Latrodectus mactans

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Identification

Family: Theridiidae

Scientific Names: Aranea mactans, Latrodectus albomaculatus, L. formidabilis, L. insularis insularis, L. i. lunulifer, L. intersector, L. mactans mexicanus, L. m. texanus, L. perfidus, L. sagittifer, Tetragnatha zorilla, Theridion lineatum, T. lineamentum, T. verecundum [Note: This is one of the 2 most geographically wide-spread & best known of at least 31 currently valid species in this genus.]

Common Names: Black Widow Spider, Southern Black Widow, red-back spider, jockey spider, Katipo, viuda negra, chiranthahua, arana brava, casampulga, la coya, arana naranja

Description

Medium-sized cobweb spider, females' body (cephalothorax + abdomen) usually 10-15 mm long, satiny dark-brown to black w/ reddish "hourglass" mark on posterior ventral abdomen, often w/ a reddish spot on dorsal abdomen just above its tip. Female abdomen rounded & globular. Males much smaller, rather slender w/ relatively long legs. Males & young often w/ varying pattern of many stripes or blotches of red, white & brown on body.

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Habitat

Most often found hanging in typical "cobwebs" in upper corners of basements, crawl spaces, outbuildings, & under seats of outdoor privies, usually near garbage or debris, wherever insect prey is abundant. Geographically wide spread. Found in southern U.S. (New York to northern California & southward), several Caribbean islands, Mexico, & Central & parts of South America.

Activity and Behavior

Mainly nocturnal, hangs in web awaiting prey, usually tries to get away from large animals & people, but will often aggressively defend its egg clusters (sacs) which it has hung in its web. Feeds on nearly any kind of insect or arthropod which gets caught in its web. Males are not always eaten after mating w/ a female, usually only if female has not fed recently, but he is often "biologically spent" & dies soon afterward anyway.

Venom Characteristics

Mainly neurotoxic (presynaptic sites). Bite usually like a pinprick, often not felt 'til 15 min. later, then pain may be locally intense. Severe envenomation causes symptoms like spreading intense pain, lots of sweating, fast & shallow breathing, eyelids swollen, alternating excess & lack of salivation, cardiac rate & rhythm changes, rigid abdominal muscles, sight impaired (seeing "light" spots). Human fatalities rare (<5%, untreated) & often due to additional medical problems.

Latrodectus spp.

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Identification

Family: Theridiidae

Scientific Names: Aranea sp. (in part), Tetragnatha sp. (in part), Theridion sp. [Note: There are at least 31 currently recognized named spp. in this genus; 8 of the most important ones are addressed separately, individually.]

Common Names: Widow spiders, Black Widows, Shoe-button spiders, jockey spiders

Description

Medium-sized cobweb spiders. Some characters vary a lot between species, sexes, & growth stages. Females w/ body (cephalothorax + abdomen) usually 8-18 mm long, males of all spp. much smaller (body usually 3-7 mm long) & thinner. Female's abdomen usually globular, satiny, dark brown to black (some spp. pale tan), most spp. w/ bright red or orange marks (hourglass-like is classic), pattern varies a lot in some spp.

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Habitat

Mainly found hanging in a coarse cobweb, in upper corners of partly sheltered, semi-dark spaces w/ presence of adequate prey (usually insects or other arthropods). Various species are found regionally throughout temperate & tropical areas world wide. Individual species usually much more restricted in their natural distribution (e.g., see individual species detailed separately).

Activity and Behavior

Mainly nocturnal. Usually hang in a coarse cobweb in upper corner of partly sheltered sites like basements, crawl spaces, under eaves, etc., wherever prey (mainly insects) are present. When any prey is caught in web, the spider rushes to it, wraps it w/ more silk, bites it (injects venom) & waits a while to suck out its body liquids (partly predigested). Hangs drop-shaped egg masses in its web to hatch. Male not always eaten after mating, unless prey is scarce.

Venom Characteristics

Neurotoxic (at pre-synaptic sites). Bite (envenomation) not usually felt for several minutes; usually causes intense local pain & can cause sweating, fast & shallow breathing, heart arhythmias, salivation, rigid abdomen, muscle spasms, sight impairment, etc. Fatalities (mainly children) have been reported for several spp., & a few occur annually, but symptoms & risk vary significantly by spider species & many other factors.

Latrodectus tredecimguttatus

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Identification

Family: Theridiidae

Scientific Names: Latrodectus argus, L. conglobatus, L. erebus, L. lugubris, L. malmignatus, L. martius, L. oculatus, L. quinqueguttatus, L. venator, Meta hispida, M. schuchii, Theridion lugubre

Common Names: Mediterranean widow spider, European widow spider, North African Widow spider, 13-spotted widow spider, ragno rosso, malmignatte, la malmignatte, roga, marmaga, bou siha, tendarman, saeuss, crna baba, crve-ni pauk, karakurt, chim

Description

Medium-sized cobweb spider, female's body (cephalothorax + abdomen) usually 9-18 mm long (male's body usually 4-7 mm long & much thinner). Female abdomen globular, very dark-brown to black, usually w/ many (typically 13, up to 17; rarely no markings) moderately large dorsal red blotches in an irregular pattern. Young w/ paler body, red, orange, & white stripes &/or spots in various patterns.

Click for Image [1]

Habitat

Mainly found outdoors, hanging in its typical cobweb in partly sheltered, partly shaded, moderately humid situations (like under an awning, crawl space, wood pile, eave, or window frame) w/ adequate populations of prey insects (or arthropods) nearby. This species is very wide spread around the Mediterranean Sea in southern Europe, northern Africa & the Middle East, also found in Russia.

Activity and Behavior

Mainly nocturnal. Usually avoids large animals & humans, but females sometimes will aggressively defend their egg sacs hanging in their web. Prey mainly on available insects or arthropods which get caught in its web. Males may be eaten by females after mating, but not always (unless female has not fed recently). Usually bite humans only if molested, stepped on, or pinched in clothing being donned.

Venom Characteristics

Neurotoxic (at pre-synaptic sites). Envenomation (bite) not usually felt for several minutes. May cause intense local pain, followed by spreading pain, sweating, lacrymation, muscle spasms, heart or breathing difficulties, impaired vision, rigid (& painful) abdominal muscle wall, sometimes nausea & vomiting. Envenomation by this species currently causes a few human fatalities annually, mainly of children (about 5% of untreated severe envenomations).

 

Latrodectus variolus

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Identification

Family: Theridiidae

Scientific Names: Latrodectus mactans (in part), L. m. variolus

Common Names: Northern Black Widow, Black Widow, shoe-button spider, hourglass spider

Description

Medium-sized cobweb spider, female's body (cephalothorax + abdomen) usually 9-11 mm long (male's body usually 4-5 mm long & much thinner). Female satiny dark brown or black, w/ distinct red or orange "broken (divided) hourglass" mark on ventral side near posterior tip of globular abdomen.

Click for Image [1] [2]

Habitat

Most often found hanging in a cobweb in an upper corner of any partly shaded, partly sheltered moderately humid site w/ prey insects (or arthropods) available nearby. This species mainly limited to Canada & northern U.S., but may also be present in (but no specimens yet documented from) Mexico. Specimens are sometimes moved in commerce.

Activity and Behavior

Nocturnal, usually hangs in its coarse cobweb in an upper corner of a shaded, partly covered site like a basement, crawl space, low building eaves, or under a privy seat, near a source of prey (insects or other arthropods). Tend to avoid large animals & humans, but female will sometimes aggressively defend egg sacs. Envenomations usually occur when spider is molested, brushed against, stepped on, or pinched in clothing being donned.

Venom Characteristics

Neurotoxic (at pre-synaptic sites). Bite like a pinprick, envenomation usually not felt for >15 min., can cause intense local pain (sometimes spreading), heart arhythmias, sweating, lacrymation, muscle spasms, rigid abdominal muscles, breathing & sight impairment (seeing light "spots"), etc. Serious human envenomations & rare fatalities (mostly children) have occurred. Calcium gluconate (IV) may reduce symptoms. Full recovery from serious envenomation may take >1 mo.

 

Leiurus quinquestriatus

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Identification

Family: Buthidae

Scientific Names: Androctonus quinquestriatus (in part), Buthus quinquestriatus, Leiurus sp.

Common Names: The death stalker, five-striped desert scorpion, Israeli yellow scorpion, yellow scorpion

Description

Medium-sized scorpion, adults up to 90 mm long. Body usually pale yellow-brownish (sometimes w/ greenish tinge), cephalothorax darker (brownish or gray-brown) than legs & post-abdomen, 5 dorsal longitudinal keels on top of first 2 abdominal segments, 5th post-abdominal segment (next to the telson) distinctly darker than remainder of abdomen & legs. Legs & post-abdomen w/ many strong, erect hairs & spines; pincers relatively long & thin.

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Habitat

Mainly found in dry habitats (deserts) on various substrate surfaces but not in loose-sand dunes, & not common near towns, nor near (nor in) houses. Often hide in small natural crevices, burrows, under stones, etc. Widely distributed across northern & central Africa & the Middle East.

Activity and Behavior

Mainly nocturnal, often hunt available prey (insects, arthropods &, occasionally, small lizards) near oases, or along edges of vegetation in desert margin sites. Ovoviviparous, young (usually 20+) hatch inside female's body & crawl out her genital opening. Young often remain w/ female & ride on her back until they are 2nd instars.

Venom Characteristics

Very potent neurotoxin, one of the world's most dangerous scorpions (partly because stings usually occur at locations very remote from necessary supportive medical care). Causes mainly localized reactions, swelling & pain in >90% of stings, but kills several humans annually. Children most severely affected because severity of venom effects are weight-dependent.

Leiurus spp.

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Identification

Family: Buthidae

Scientific Names:

Common Names:

Description

Habitat

Activity and Behavior

Venom Characteristics

 

Leptomicrurus collaris

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Identification

Family: Elapidae

Scientific Names: Elaps collaris, Hemibungarus collaris, Leptomicrurus collaris breviventris, Micrurus collaris

Common Names: Guianan black-backed coral snake, Guianan slender coral snake, coral, cobra coral, costa-preta, espalda-negra, Kraalslang, krarasneke, la negra, vibora de coral

Description

Slender, dark, terrestrial coral snake adults usually <40 cm long (max. 45.6 cm). Body mostly dark dorsally w/ a distinctive pattern of 35-50 oval white, yellow, or orange-red blotches on black or dark brown venter. This species lacks body rings, & the head & dorsum are black or very dark-brown w/ a red, white, or yellow neck ring; tail short, one pair of fixed upper front fangs. Dorsal scales are smooth & in 15 mid-body rows.

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Habitat

Found mainly in lowland rainforest & lower montane wet forests from near sea level up to 800 m elevation. Limited to Caribbean & Atlantic coastal countries of northern South America.

Activity and Behavior

Mainly nocturnal, at least semi-fossorial (burrowing) in sandy soil & accumulations of forest litter. Oviparous, clutch size not documented. Reportedly prey mainly on available lizards, other snakes, & invertebrates.

Venom Characteristics

Not much known, probably mainly neurotoxic. Venom is injected through grooved, fixed front fangs. Due to the small size of their mouth, this species could probably only bite humans on a finger, a toe, or in webbing between such digits. No serious human envenomations or fatalities reported due to bites by this species.

 

Leptomicrurus narduccii

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Identification

Family: Elapidae

Scientific Names: Elaps melanotus, E. narducci, Leptomicrurus narducci melanotus, L. n. narducci, Micrurus narduccii

Common Names: Andean black-backed coral snake, Andean slender coral snake,cobra coral costa preta Andina, coral, coral espalda negra Andina, coralillo, culebra de dos cabezas, Coral, Naca-Naca, yamong

Description

Adults usually 30-60 cm long (max. 110 cm); body usually uniformly black dorsally, except for a pale (usually yellow) ring around the neck; some rare specimens also have 2-8 very narrow pale rings around the body (look like thin cross-stripes dorsally), usually mid-dorsally & toward the tail, & a fairly short tail. Belly w/ 38-62 obvious oval orange, red or yellow blotches on a black background. Has a pair of fixed upper front fangs.

Click for Image [1]

Habitat

Mainly found in lowland rainforest & lower montane wet forest, usually in accumulated leaf litter in shaded sites at 100-1,500 m elevation.

Activity and Behavior

Mainly nocturnal, at least partly fossorial (burrowing) in soft soil or forest litter. May raise & curl tail when disturbed. Seldom seen & usually not aggressive; most bites occur during attempts to capture the snake. Oviparous, usually <20 eggs per clutch. Mainly prey on available lizards, invertebrates or other small snakes.

Venom Characteristics

Mainly neurotoxic venom which can be injected through grooved fixed front fangs. Due to the small size of their mouth, bites to humans by this species usually occur on a finger, toe or webbing between those. No serious human envenomations or fatalities reported to have been caused by this species, so far.

 

Leptomicrurus renjifoi

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Identification

Family: Elapidae

Scientific Names:

Common Names: Ringed slender coral snake, coral

Description

Small, slender coralsnake, adults about 42 cm long. Unusual pattern for a coral snake, body w/ roughly equally wide, alternating black & pinkish-orange rings. Has a pair of fixed upper front fangs, & fairly short, relatively blunt tail. Only 2 specimens known.

Habitat

Found in leaf litter in a gallery forest by the river Rio Tomo, in northeastern Colombia; at that location, the river was flanked by savannah & grain fields. Only known from that single locality in Colombia.

Activity and Behavior

Unknown, but probably similar to other related species; being mainly nocturnal, terrestrial (semi-fossorial), not aggressive, oviparous, & predatory on a variety of small, locally available lizards, invertebrates & other snakes.

Venom Characteristics

Not known, but probably neurotoxic. No human bites nor envenomations reported.

 

Leptomicrurus scutiventris

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Identification

Family: Elapidae

Scientific Names: Elaps scutiventris, Leptomicrurus schmidti, Micrurus karlschmidti, M. narducci (in part)

Common Names: Pygmy slender coral snake, pygmy black-backed coral snake, coral, cobra-coral preta pequena, coral negra pequena

Description

Small, slender, dark coralsnake, adults usually 30-40 cm long (max. 44.5 cm). Head & body uniformly dark brown to black dorsally, except for a pale (white, yellow, or reddish) ring at the back of the head & another near the tail tip. Belly dark brown w/ 24-38 rounded yellow, orange or red blotches; these blotches sometimes have blackish speckling. Has a pair of fixed upper front fangs & a relatively short tail.

Habitat

Found mainly in pluvial forests & lower montane wet forests of the Northwestern Amazon basin. Mainly a lowland species, but has been reported up to 1,200 m elevation.

Activity and Behavior

No data. Coral snakes usually are nonaggressive; most bites occur during attempts to capture the snake.

Venom Characteristics

Mainly neurotoxic venom which can be injected through grooved, fixed front fangs. Due to the small size of their mouth, bites to humans by this species usually occur on a toe or finger. No serious human envenomation or fatality reported as caused by this species, so far.

 

Lonomia achelous

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Identification

Family: Saturniidae

Scientific Names: Lonomia diabolous, Lonomia obliqua (in part), Phalaena achelous

Common Names: Stinging caterpillar

Description

Larvae are large, often 50+ mm long in 6th (largest) stage (instar). Very spiny, thick-bodied, usually greenish-brown w/ dark brown or black head capsule. Younger instars lighter green (darken w/ age), eggs pale greenish-yellow, barrel-shaped, laid in clusters on suitable host plant leaf or stem. Adults dull, various shades of pale to medium-brown, w/ wings held partially closed at rest & greatly resembling a dead leaf, w/ a darker "midrib" stripe from wing-tip to wing-tip.

Click for Image [1] [2]

Habitat

Larvae are found on several species of trees & woody shrubs; most active feeding at night on host leaves, gather in clusters & remain inactive on lower trunk or branches of host plant during the day. Known distribution includes most of northeastern & central South America, from northern Argentina & northern Brazil to Venezuela & Peru; not yet reported from Bolivia or eastern (Amazonian) Ecuador, but probably occurs there.

Activity and Behavior

Nocturnally active larvae eat leaves of various woody shrubs & trees. They congregate & remain inactive, clustered on trunks or lower branches of the same plants, during the day. Larvae are covered w/ strong, pointed, many-branched hollow spines. Venom in those spines (spicules) is passively injected into any intruder when the spine tips stick into it & are broken off there.

Venom Characteristics

Very potent anticoagulant & pro-coagulant factors, & possibly other factors affecting blot clotting. Very minor dermal contact w/ a L. achelous larva usually causes immediate burning sensation, & within a few hours, discomfort, weakness, headache, & various external & internal bleeding (w/ opening of any partially-healed wounds). Acute renal failure (ARF) or cerebral hemorrhage can cause human deaths (many each year). Eggs, pupae & adults do not cause such effects.

 

Lonomia obliqua

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Identification

Family: Saturniidae

Scientific Names: Lonomia achelous (in part), Phalaena achelous (in part)

Common Names: Stinging caterpillar, electric caterpillar

Description

Larvae are large, w/ largest (6th) stages (instars) averaging 53.5 mm long, very spiny, thick-bodied, usually greenish-brown w/ a dark-brown to blackish head capsule. Younger instars usually lighter green, Eggs pale green, somewhat barrel-shaped, laid together on host plant stems or leaves. Adults have various shades & patterns of dull brown, rest w/ wings partly folded & very much resemble dead leaves, w/ a distinct dark "midrib" line from wing-tip to wing-tip.

Click for Image [1] [2]

Habitat

Larvae are found on several species of trees & woody shrubs (most actively feeding on leaves at night; congregated in large inactive groups on trunks & lower branches during the day). This species is mainly (possibly only) found in southern Brazil.

Activity and Behavior

Nocturnally active larvae eat leaves of certain woody shrubs & trees. They congregate & remain inactive, clustered on trunks or lower branches of the same plants, during the day. Larvae are covered w/ multi-branched, strong, pointed, hollow spines. Venom is passively injected through those spines (spicules) into intruders who contact & break the tips off. Humans are envenomated (sometimes fatally) when they step on, or merely brush against, a larva.

Venom Characteristics

Very potent venom w/ anticoagulant, pro-coagulant, & several additional factors affecting blood clotting. Dermal contact w/ a L. obliqua larva usually causes immediate burning sensation, & within a few hours, discomfort, weakness, headache, & various external & internal bleeding (w/ re-opening of any partially-healed wounds). Acute renal failure (ARF) or cerebral hemorrhage have caused human deaths (many each year). Eggs, pupae & adults not known to cause any such effects.

Lonomia spp.

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Identification

Family: Saturniidae

Scientific Names: Lonomia (formerly Phalaena) spp. [ There are currently 5 recognized species in this genus, mainly distributed throughout northern South America, w/ one species also occurring throughout Mexico & Central America, & one limited to southern Brazil. All can "sting," but only two species (detailed separately) are known to cause human fatalities.]

Common Names: Stinging caterpillars, electric caterpillars

Description

Larvae usually grow to 50+ mm in their largest (6th) stage (instar). Very spiny, thick-bodied, & usually greenish-brown w/ dark head capsules when fully grown. Younger instars are usually lighter greenish-brown. Eggs usually pale greenish, laid in clusters on host plant stems or leaves. Adults dull brownish, hold wings partly closed at rest, & look very much like dead leaves w/ a dark "midrib" stripe from wing-tip to wing-tip.

Habitat

Larvae usually found on various species of host plant shrubs or trees, actively feeding on upper leaves at night; inactive & clustered on stem or lower branches during the day. Mainly limited to central & northern South America (east of the Andes) & Central America, w/ 1 species found in Mexico.

Activity and Behavior

Nocturnally active larvae eat leaves of various host plants (usually woody shrubs or trees). They congregate & remain in inactive clusters on stems, trunks or lower branches of host plants during the day. Larvae are covered w/ strong, sharp-pointed, multi-branched, hollow spines containing their venom; which is passively injected when any intruder breaks off any spine tips in itself (usually in its skin).

Venom Characteristics

Contains very potent anticoagulant, pro-coagulant, & possibly other clot-inhibiting factors. Very minor dermal contact w/ a larva can cause immediate intense burning sensation, & within hours, discomfort, weakness, headache, & various external & internal bleeding (often re-opening any partially-healed wounds). Acute renal failure & cerebral hemorrhage can cause human deaths (many per year, by two species). Eggs, pupae & adults do not cause such effects.

 

Loxosceles deserta

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Identification

Family: Loxoscelidae

Scientific Names: Loxosceles unicolor (in part)

Common Names: Desert brown spider (North American), desert fiddle-back spider

Description

Adult females' bodies average about 9 mm long (males smaller), w/ relatively longer, thinner legs than most spiders, 2nd pair longest in this species. Body light-gray, tan or medium brown w/ darker brown "fiddle-shaped" mark on top of cephalothorax, w/ 3 pairs of eyes (diads) along the fiddle's front edge. No distinct contrasting stripes, spots or darker strong spines on legs or body. Closely resembles L. reclusa, but slightly smaller & paler, w/ relatively slightly longer legs.

Habitat

Found mainly in arid desert sites, below 5,000 ft. (1,500 m) elevation. Wide-spread in the Mojave & Sonoran Deserts of southern Utah, Nevada, California, Arizona & Baja California Norte (probably also occurs in adjacent Sonora but no specimens known from there, so far).

Activity and Behavior

Nocturnal, unless a large population is present. Usually spin irregular webs in crevices & openings alongside or under stones, logs, or available "chunks" (large physical pieces) of debris in dry desert margin situations. Tend to stay in contact w/ that web except when trying to capture prey nearby. Essentially behave as "wandering hunters" foraging out from their moderately open, sparsely-webbed retreat to capture locally available insects or arthropods.

Venom Characteristics

Contains potent cytotoxic, hemotoxic & neurotoxic factors (& hyaluronidase). Envenomation causes various effects in humans, from limited, localized cutaneous (& underlying tissue) necrosis; to spreading, progressive, much deeper tissue necrosis (very slow to heal); to death. Human fatalities have not been documented due to venom of this species, but serious, extensive tissue necroses have been reported, & venom of closely related species, like L. reclusa, has proven lethal to humans.

Loxosceles gaucho

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Identification

Family: Loxoscelidae

Scientific Names: Loxosceles laeta (in part)

Common Names: Brown spider, violin spider, "Gaucho Spider"

Description

Adult females usually w/ body 7-12 mm long (up to 14 mm) w/ males smaller than females. Body usually pale to dark-brown (often w/ reddish tinge), w/ slightly darker "violin-shaped" dorsal mark on carapace, w/ its base at anterior edge. Only 6 eyes (in 3 pairs, or diads) along the "violin's" base. Legs relatively long & slender, w/ no marks, stripes or obvious darker spines. Looks very much like L. laeta, but most specimens darker or more reddish where the 2 spp. occur together.

Habitat

Mainly found in dark, fairly warm, fairly dry, undisturbed sites, often under loose bark, or in crevices beneath stones or logs. Often live around the outsides of (& even inside) houses in central & southern Brazil (e.g., Sao Paulo). May be moved in commerce.

Activity and Behavior

Nocturnal, usually spin irregular webs in cracks, crevices, & "corners" along or under large rocks, logs or items of solid debris, then stay in contact with that webbing except to forage out short distances & capture insects or arthropods which wander nearby. Tend to avoid humans or other large animals, but will bite defensively if pinched or bothered.

Venom Characteristics

Not well known, but probably contains cytotoxic, haemotoxic, & neurotoxic factors. Bites (& envenomations) of humans are usually due to the spider being molested, pinched, rolled onto or trapped inside clothing being donned. Human fatalities have been reported from bites of this species.

Loxosceles intermedia

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Identification

Family: Loxoscelidae

Scientific Names: Loxosceles laeta (in part)

Common Names: Brown spider, violin spider

Description

Female usually w/ body 7-12 mm long (up to 14 mm), male smaller. Body usually light-tan to dark-brown, w/ slightly darker "violin-shaped" dorsal mark on top of carapace (w/ 3 pairs of eyes along violin's base at front margin), abdomen often grayish-brown. Legs fairly long, slender & w/ no marks, stripes, bands or obvious dark spines. Looks very much like L. laeta, but usually slightly smaller in areas where they both occur.

Habitat

Mainly found in dark, protected, fairly dry, crevices in warm regions at low elevations (below 500 m). Commonly found around & inside humans' homes, mainly in central & southern Brazil. Overlaps part of the range of L. laeta, but they are seldom found in same local habitats (L. latea predominate inside "drier," wooden buildings).

Activity and Behavior

Mainly nocturnal, mainly a wandering hunter type predator on available insects or arthropods. Usually spin only a loose web in their harborage crevices or to cover eggs. Usually avoid humans & other large animals, but will bite defensively if molested, pinched, rolled onto, stepped on, or trapped in clothing being donned.

Venom Characteristics

Mainly potent cytotoxic, neurotoxic, & hemotoxic factors. Envenomation usually causes significant local pain, redness & inflammation, & local tissue necrosis. Systemic effects (sometimes delayed 1-5 days) may include spreading tissue necrosis, cardiac problems, distant vascular collapse & small hemorrhages, acute kidney failure & death. Causes a number of human fatalities each year within its range.

Loxosceles laeta

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Identification

Family: Loxoscelidae

Scientific Names: Scytodes laeta, Scytodes nigella, Scytodes rufipes

Common Names: Brown spider (South American), (Chilean) violin spider, Chilean Recluse, Chilean fiddle-backed spider

Description

Adult female's body usually 12 mm long (up to 15 mm), male usually smaller. Carapace & appendages bright yellowish to orange or reddish-brown. Abdomen grey to white, covered w/ black hairs, giving it a dusky appearance. Eyes relatively smaller than those of the "L. reclusa group," 3 diads in a strongly recurved row (along the base of the "fiddle-shaped" dorsal mark), 4th pair of legs distinctly longer than any other pair.

Click for Image [1]

Habitat

Mainly found in fairly dry (sometimes in seasonally moist) sites, often transported in commerce & found in drier, less actively occupied parts of humans' structures (e.g., in edges of garages or closet, or among & under stored boxes or furniture). Original natural distribution was probably limited to northwestern South America, but now very wide spread (usually established in open dry, heated buildings in temperate regions). Specimens reported from Australia & Finland.

Activity and Behavior

Mainly nocturnal, usually spins irregular web in corners (when in buildings) or in cracks under edges of stones logs, blocks, etc. Usually remains in contact w/ web except to forage out short distances to catch prey insects or arthropods which happen nearby.

Venom Characteristics

Contains potent cytotoxic, hemotoxic, & neurotoxic factors (& hyaluronidase). Envenomation usually causes at least some local tissue necrosis around bite site, well documented to cause serious spreading human tissue destruction (necrosis), & occasional human deaths.

Loxosceles reclusa

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Identification

Family: Loxoscelidae

Scientific Names: Loxosceles rufescens (in part), Loxosceles rufipes (in part). [Note: This in the species of this genus most commonly encountered by humans in North America. Of the 70 described species in this genus, 50 are found in the Americas (14 in the U.S.). A few are found (rarely) in Europe & in Africa.]

Common Names: Brown recluse spider, fiddle-back, violin spider, brown spider

Description

Adult female typically w/ body 7-12 mm long (male smaller), various shades of brown from grayish-tan to nearly black, w/ only 6 eyes in 3 pairs (diads) along front margin of dorsum (along base of distinct "fiddle-shaped" mark, which is usually slightly darker than background body color). No other distinct, contrasting stripes or spots on the body, nor on any legs. Legs thin, 2nd pair usually longest, no strong spines on legs or body.

Click for Image [1] [2]

Habitat

Mainly found in dark, undisturbed corners or cracks (often indoors or within structures), w/ fairly warm temperatures (65-80 degrees F). Natural distribution limited to a big oval-shaped area of central & southeastern U.S. (from Iowa south to Arkansas, Louisiana, & east to Alabama, most of Tennessee & Kentucky). Sometimes moved to other areas in commerce, but seldom establish more than temporary populations (usually only indoors) there. May occur in Mexico, but no confirmed specimens so far.

Activity and Behavior

Mainly nocturnal unless local population is very large. Mainly a wandering hunter preying on insects & other available arthropods. Builds only limited webbed retreats or protective web coverings for eggs.

Venom Characteristics

Mainly cytotoxic (several different such factors), often causing serious local & progressive tissue necrosis; also includes potentially lethal neurotoxic factors. A number of serious slow-healing wounds (necrotic arachnidism), sometimes including very large body areas occur yearly within its range, & occasional human deaths have been reported from envenomation by this species. Symptoms of an antibiotic-resistant bacterium (MRSA) can resemble surface effects of this spider's bites.

Loxosceles rufescens

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Identification

Family: Loxoscelidae

Scientific Names: Scytodes rufescens, Loxosceles marylandica

Common Names: The Mediterranean Recluse, Brown spider, violin spider

Description

Female w/ body usually 7-12 mm long (up to 15 mm). Usually medium-brown to dark chestnut-brown, w/ slightly darker brown "violin shaped" mark on top of carapace (its base along the front margin). Only 6 eyes (in 3 pairs, or diads) around the front edge of the "violin's" base. Abdomen often lighter, legs fairly long, slender & w/ no marks, stripes or obvious strong spines. Usually looks very much like L. reclusa but carapace darker & usually reddish-brown.

Click for Image [1]

Habitat

Found mainly in fairly dry, warm, cryptic, dark, undisturbed sites, often in crevices/ narrow spaces under or beside logs, stones, boxes, or wall voids. Frequently found in sub-basements of older, heated large buildings in temperate zones. Reportedly originated in Mediterranean Europe & N. Africa, but now wide spread in tropical, sub-tropical & many temperate areas (may be nearly cosmopolitan in buildings). Sometimes found outdoors under loose bark near ground level in warm regions.

Activity and Behavior

Mainly nocturnal, "wandering hunter," typically preying on locally available insects & arthropods. Builds only a loose web in or near harborage (usually in crevices beside or under logs, stones, boxes, etc.), or to cover a clutch of eggs. Usually one of the most reclusive species in this genus & seldom encountered by humans.

Venom Characteristics

Contains moderately potent cytotoxic, hemotoxic, & neurotoxic factors. Very few human envenomations, & no well-documented human fatalities, reported as having been caused by envenomation by this species. But often misidentified as L. reclusa, or other Loxosceles spp.

 

Loxosceles spp.

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Identification

Family: Loxoscelidae

Scientific Names: Scytodes spp. [Note: This genus currently includes about 70 recognized named species, w/ about 50 found mainly in the Americas, another 15 found mainly in Africa, & at least 3 which have obviously been translocated widely by commerce (2 spp. have repeatedly established populations in heated buildings in sites far too cold for an outdoor population to survive over winter).]

Common Names: Brown spiders, violin spiders, fiddle-back spiders, "Brown Recluse" spiders

Description

Medium-sized spiders, females of most spp. w/ body usually 6-14 mm long. Usually some shades of brown (tan to very dark brown), w/ a slightly darker "violin-shaped" mark on top of the carapace, & w/ its base at the front (anterior) edge of the carapace. No other distinct marks, stripes or bands on body or legs. Only 6 eyes, in 3 pairs (diads), around the "violin's" base. Abdomen often lighter colored. Legs fairly long & slender, lacking obvious spines, stripes, or spurs.

Habitat

Exact typical local habitat (& natural species range) varies w/ individual species. Most spp. are mainly found in dark, fairly warm, fairly dry, protected (cryptic) sites, which are relatively undisturbed & have adequate insect (arthropod) prey available. Some spp. often establish populations (sometimes very large numbers) inside buildings. Found throughout much of the tropical, subtropical & some temperate zones of the world.

Activity and Behavior

Mainly nocturnal, unless local population is very large. Mainly "wandering hunter" type predators on available insects or arthropods. Usually spin only a limited loose web in, or at the mouth of, a crevice or similar retreat, females may spin a sheet of web to cover their clutch of eggs.

Venom Characteristics

Contains potent tissue necrotic, neurotoxic, haemotoxic &, in some spp., also cardiotoxic factors. Envenomation by some spp. may cause intense local pain, but more often seems like a "pin-prick." Venom of this genus nearly always causes some tissue necrosis (often progressively spreading) at a bite site. Systemic effects can be delayed 1-24 hrs., & sometimes include acute renal (kidney) failure &/ or cardiac problems.