An Insect Virus 



tus LIparis. All my tests, with not a single 

 exception, brought about stinging, of various 

 degrees of violence, it is true. I attribute 

 these differences in the result to the greater 

 or lesser quantities of the virus employed, for 

 it is impossible to measure the dose. 



So the urticating excretion is common to all 

 the caterpillars. By a very unexpected rever- 

 sion of the usual order of things, the popular 

 repugnance is well-founded; prejudice be- 

 comes truth: all caterpillars are venomous. 

 We must draw a distinction, however: with 

 the same venomous properties, some are inof- 

 fensive and others, far less numerous, are to 

 be feared. Whence comes this difference? 



I note that the caterpillars marked out as 

 stinging live in communities and weave them- 

 selves dwellings of silk, in which they stay for 

 long periods. Moreover, they are furry. Of 

 this number are the Pine Processionary, the 

 Oak Processionary and the caterpillars of 

 various Lipares. 



Let us consider the first-named in parti- 

 cular. His nest, a voluminous bag spun at 

 the tip of a branch, is magnificent in its silky 

 whiteness, on the outside; inside, it is a dis- 

 gusting cesspit. The colony remains in it all 



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