Field Guide to Venomous and Medically Important Invertebrates ...

which resolves within a few days. Some protein-feeding ants such as the Pharaoh ant,
Monomorium pharaonis, have been incriminated as mechanical vectors of pathogens in
hospitals. Army ants (Eciton hamatum), despite the threat idealized in the mass media, are
harmless to humans. However, the majors (large workers) have formidable mandibles and can
inflict a fairly painful defensive bite.
Fig. 131. Head of an army ant. Photo: Sean Brady.
Lepidoptera
(moths)
Of the some 300,000 species of Lepidoptera known worldwide, about 100 species or so are
capable of producing severe reactions in people who contact the urticarial setae of the caterpillars
and occaioanlly the adult moths. These dangerous caterpillars belong to the families
Limacodidae, Lymantriidae, Megalopygidae, Saturniidae, and Thaumetopoeidae. Caterpillars in
these families are distributed worldwide in temperate and tropical environments.
Urticarial reactions are generally broken into two broad groups termed lepidopterism caused by
contact with the adult stage, egg cases and pupal cocoons, and erucism caused by contact with
larvae. The setae or ―hairs‖ of some adult moths, their egg cases, or pupal cocoons may produce
irritating contact dermatitis. Contact with moth setae or urticating setae of larvae can produce
reactions ranging from a mild burning sensation to extreme pain lasting upwards of 12 hours, and
residual pain lasting for up to two weeks. The initial pain is often followed by reddening of the
skin, dermatitis with lesions, blisters or pustules, reddened wheals, localized swelling and rash at
the envenomation site, and itching. Conjunctivitis may occur when the eyes are involved.