ABSTRACT
Many of the common hairy caterpillars in this country when handled ‘sting’ with their hairs just as the nettle and primula do. The hair penetrates some layers of the skin and breaks off, leaving a little piece projecting. If the hand is passed over the face the stumps of hair projecting from the skin sting the face in a similar manner. Soon an intolerable itching begins, more extensive than the parts actually irritated; vigorous rubbing goes on until in a short time the arms, face, neck, and often chest become covered with a red eruption in which minute nodules can be detected. The hairs and the poison may even be transferred (as Mr Lawford has shown in the case of Bombyx Rubi) to the conjunctiva, the hair ultimately becoming encapsuled in a little nodule of fibrous tissue. The rash is often attended with considerable swelling and slight rise of temperature, and, as Dr Dukes of Rugby pointed out, may lead to an erroneous diagnosis of rötheln. It would be well if medical officers of schools warned the boys of the caterpillars which should not be handled and of the risk they run in rubbing themselves when the skin is irritated. The chief British offenders are the common ‘woolly bear’, the caterpillar of the tiger moth (Arctia caia), and its near relations; almost all the Bombyx group, including the oak eggar, fox moth, drinker and lappet moths; and the Liparis group, including the common ‘gold tail’ and ‘brown tail’. The hair of some foreign caterpillars has much more severe effects. Gangrene has been reported from contact with the hairy Indian Shoa Pokâ, and the Australian Lasiocampa vulnerans is credited with producing fatal results. On the Continent there is a very common caterpillar, the Bombyx processionea, which fortunately does not appear to have reached this country. The erythema resulting from contact with it is followed by severe general symptoms, and in the case of one boy in the south of France, whose case was detailed in The Lancet, after a number of caterpillars had fallen on his chest while climbing a tree, there ensued violent irritation, general swelling, fever, somnolence, delirium, and death in a few hours in spite of energetic medical treatment. Although fortunately we do not meet with such severe cases in this country, the effects are so unpleasant to the victim and the diagnosis is often so difficult for the practitioner that a word of warning to those most likely to suffer will not be superfluous.
