Venomous Arthropods And Their Associated Problems

Envenomization Can be divided up into 2 categories: (1) Passive Envenomization (2) Active Envenomization

Envenomization - Action of Venom Neurotoxin (black widow spider)Neurotoxin (black widow spider) Cytolytic, hemolytic (brown recluse spider)Cytolytic, hemolytic (brown recluse spider) Hemorrhagic (moth larvae)Hemorrhagic (moth larvae) Vesicating/blistering (blister beetles)Vesicating/blistering (blister 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 Hymenoptera

Red Imported Fire Ant

Fire Ant Mounds

Red Imported Fire Ants The pathognomic pustules following a fire ant envenomation.

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. Scorpions

Bites (1) Spiders –Black Widow –Brown Recluse –Hobo Spider (2) Centepedes

SPIDERS Black Widow Tarantula Brown Recluse Hobo Fiddle Hourglass

Latrodectus mactans (Black Widow)

Loxosceles reclusa (Brown Recluse)

Progression of Bite (3-10 days)

Tegenaria agrestis (Hobo Spider or Aggressive House Spider)

Hobo Spider Bites

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

Lycosa tarantula Lycosa 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!

Centepedes Class: Chilopoda 20 families and over 2500 species. 1-pair of legs per body segment. Most small, a few are 10 inches or longer. 1 st pair of legs are modified fangs.

Scolopendra gigantea

Other Methods (1) Millipede (2) Blister Beetles (3) Bombardier Beetles (4) Caterpillars (Moths)

Millipedes - 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 - Lepidoptera Problems Caused by Adult Moths DermatitisDermatitis Respiratory Distress (Asthma)Respiratory Distress (Asthma) Lachrymal and blood-feedingLachrymal and blood-feeding Problems 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 moth Automeris io [Costa Rica]

Clues for Diagnosing Arthropod Envenomizations