Venomous Arthropods

And Their Associated Problems

Envenomization

• Can be divided up into 2 categories:

• (1) Passive Envenomization

• (2) Active Envenomization

Envenomization - Action of VenomEnvenomization - Action of Venom

• Neurotoxin (black widow spider)Neurotoxin (black widow spider)

• Cytolytic, hemolytic (brown Cytolytic, hemolytic (brown recluse spider)recluse spider)

• Hemorrhagic (moth larvae)Hemorrhagic (moth larvae)

• Vesicating/blistering (blister Vesicating/blistering (blister beetles)beetles)

Stingers

• (1) Honey Bee

• (2) Bald Faced Hornet

• (3) Paper Wasps

• (4) Yellow Jacket

• (5) Red Imported Fire Ant (Solenopsis invicta)

• (6) Scorpions

Venomous HymenopteraVenomous Hymenoptera

Red Imported Fire AntRed Imported Fire Ant

Fire Ant MoundsFire Ant Mounds

Red Imported Fire AntsRed Imported Fire AntsThe pathognomic pustules following a fire ant envenomation.

Velvet Ants “Cow Killers”Velvet Ants “Cow Killers”

• Scorpions are easily distinguished from other arachnids by their large, well developed claws and distinct division of the abdomen into a broad preabdomen and narrow, tail-like postabdomen.

• All scorpions are venomous, but only about 25 species worldwide possess venom of sufficient toxicity to kill humans

• The venoms with severe toxicity are usually neurotoxins.

ScorpionsScorpions

BitesBites

• (1) Spiders– Black Widow– Brown Recluse– Hobo Spider

• (2) Centepedes

SPIDERSSPIDERS

Black WidowBlack Widow

TarantulaTarantulaBrown RecluseBrown Recluse

HoboHobo

FiddleFiddle

HourglassHourglass

Latrodectus mactansLatrodectus mactans (Black Widow)(Black Widow)

Loxosceles reclusaLoxosceles reclusa (Brown Recluse)(Brown Recluse)

Progression of Bite (3-10 days)Progression of Bite (3-10 days)

Tegenaria agrestisTegenaria agrestis (Hobo Spider or Aggressive House Spider)(Hobo Spider or Aggressive House Spider)

Hobo Spider BitesHobo Spider Bites

Distribution of venomous spiders causing necrotic Distribution of venomous spiders causing necrotic ulceration - United States and Canada.ulceration - United States and Canada.

Lycosa tarantulaLycosa tarantula (Wolf Spider)

• Occur in Europe and not the U.S.

• Not a Tarantual!

• 1370 recorded biting humans.

• Tarantism

• Dance called the tarantella

Tarantulas

• 840 described species• Fangs larger than those

of most venomous snakes.

• Old world species more venomous than new world species.

• Neurotoxic

• Most species are harmless!

CentepedesCentepedes

• Class: Chilopoda

• 20 families and over 2500 species.

• 1-pair of legs per body segment.

• Most small, a few are 10 inches or longer.

• 1st pair of legs are modified fangs.

Scolopendra giganteaScolopendra gigantea

Other MethodsOther Methods

• (1) Millipede

• (2) Blister Beetles

• (3) Bombardier Beetles

• (4) Caterpillars (Moths)

Millipedes - Class DiplopodaMillipedes - Class Diplopoda• Millipedes (2 legs/body segment) do not have biting mouthparts or

fangs. Their medical importance comes from their ability to secrete an irritating defensive liquid from pores along their sides.

• Such secretions contain benzoquinones, aldehydes, hydrocyanic acid, and other substances.

Blister Beetles

• Family: Meliodae

• Cantharidin

• Livestock come in contact with blister beetles.

• Spanish Fly

Bombardier Beetles

• Family: Carabidae

• ½ inch long.

• Chemical defense

• 70 rapid shots

• 100C (212F)

• Southern California

Bombardier Beetles

Venomous Insects - LepidopteraVenomous Insects - Lepidoptera

Problems Caused by Adult MothsProblems Caused by Adult Moths

• Dermatitis Dermatitis

• Respiratory Distress (Asthma)Respiratory Distress (Asthma)

• LachrymalLachrymal and blood-feeding and blood-feeding

Problems Caused by Larval MothsProblems Caused by Larval Moths

• DermatitisDermatitis

• Stinging envenomization - allergyStinging envenomization - allergy

• Hemorrhagic manifestationsHemorrhagic manifestations

Larval Moths Known to Cause Problems to Humans

• Urticating or "stinging" spines and setae.

• Average sensitivity– stinging sensations

• Extreme sensitivity– Severe pain and allergic reactions.– Cases are known of hospitalization– Skin bleeding (poison spines containing an

anticoagulant)

Lonomia electra

[Costa Rican species]

Puss Caterpillars

• Megalopyge opercularis

• Florida Species• long, silken, brownish

hairs.• short, poisonous

spines.• burning sensation, as

painful as a bee sting.

Puss caterpillars. The caterpillar at the left is fully grown; the one at right is still developing, note the recently shed (and still urticaceous) skin beside the larva.

Saddleback Caterpillar

Sibine stimulea

The io mothThe io moth

Automeris ioAutomeris io[Costa Rica]

Clues for Diagnosing Clues for Diagnosing Arthropod EnvenomizationsArthropod Envenomizations