POISONOUS INSECTS AND THEIR RELATIVES 427 



The female fleas burrow into the flesh, especially be- 

 neath the toe nails, where the presence of the insect causes 

 swelling and finally ulceration that often terminates 

 fatally. 



In the order Lepidoptera, composed of the butterflies 

 and moths, we find certain caterpillars with protruding 

 "horns" or filaments that strike terror to the hearts of 

 many timorous people. The tomato worm, with the 

 horn near the posterior end of the body, is looked 

 upon with great fear under the delusion that this horn 

 possesses deadly poisoning power. As a matter of fact, 

 the tomato worm and its similarly appearing relatives 

 are perfectly harmless creatures. So it is with the thou- 

 sands of other various species of caterpillars found in 

 North America with the exception of perhaps 18 or 20. 

 C. V. Riley, in his Fifth Missouri Report, gives a list of 

 fifteen stinging or urticating caterpillars. To this list 

 we must now add the caterpillar of the brown-tail moth 

 and a few others of slight irritability. So that out of the 

 more than six thousand species of caterpillars in America 

 north of Mexico we shall not find more than 18 or 20 that 

 are poisonous and none of these, so far as the author is 

 aware, with the exception of the brown-tail moth, is 

 really to be considered as very serious. 



The few caterpillars that possess nettling or urticating 

 powers bear sharp, penetrating, poisonous spine-like 

 setae. In several species, the spines of these caterpillars 

 produce distinct irritation and annoyance whenever they 

 come in contact with the skin. 



Notable among these are the caterpillars of the flannel 

 moths, especially Lagoa crispata. The caterpillars of this 

 moth are from three-quarters of an inch to an inch in 



