POISONOUS INSECTS AND THEIR RELATIVES 433 



the pupal stage for about twenty days, when the moths 

 appear. 



The moth is snow-white except for a brownish shade on 

 the back of the abdomen and a large globular tuft of golden 

 brown hairs on the end of the body. It is this tuft of 

 conspicuous brown hairs that gives it the name brown- 

 tail moth (Plate VII). 



The caterpillar, when full-grown, is an inch and a half 

 to an inch and three-quarters in length, reddish-brown in 

 color, with a broken white line along each side, and two 

 red tubercles on the back near the posterior end. The 

 body is covered with long, branching, brittle hairs, and 

 bears many very short, small ones which are barbed and 

 constitute the nettling hairs. 



Wherever these caterpillars are in abundance in the 

 vicinity of human beings, a disease, known as " brown-tail 

 rash " appears. The disease affects mostly the neck, hands, 

 and face, although it may break out all over the body. 

 It begins with an intense irritation followed by eruption 

 resembling eczema, each eruption with a watery blister 

 on top. Sometimes large pustules containing pus form 

 on the skin. The first attack usually lasts a week or ten 

 days. One can, however, be poisoned as often as the 

 caterpillars strike the skin. The trouble is said to be 

 much worse than that caused by poison ivy, and harder to 

 eradicate. It does not, except possibly in rare cases, 

 when combined with other troubles, terminate fatally. 

 It seems to be especially severe on persons suffering from 

 dropsy and tuberculosis. The disease is caused by the 

 nettling hairs of the caterpillars penetrating the skin. 

 It may be contracted simply by coming in the vicinity of 

 the caterpillars, although not in actual contact with them, 

 2f 



