AQUATIC INSECT'S IN NEW YORK STATE 



475 



;a suitable place to pass the pupa state. Walsh gives an account 

 •of the crawling of the mature larvae to the top of a chimney 

 of a small house by the Mississippi river. 



When the last larval skin is shed, the pupa is very light brown 

 or nearly white, but gradually becomes darker up to the end 

 of the period. The pupa very much resembles the adult in ex- 

 ternal structure, specially as regards the antennae, tarsal seg- 

 ments, wing pads, and absence of lateral filaments, spongy tufts 

 and prolegs. There is great variation in the appearance of the 

 warty prominences left by the bases of the filaments. 



The length of the pupal life was determined by daily observa- 

 tion of specimens which had just crawled from the water to 

 find a nest for the pupal life. The transformations of 25 speci- 

 mens were thus noted. It was found that the time spent in 

 the nest before the larval skin is shed varies from about one 

 day to as much as two weeks. The time from this last molt 

 till the adult emerges, or the actual life of the pupa, is not so 

 -variable, as the table will show. 



It will be noticed from the table that the length of life in 

 this state varies from seven to 14 days with an average of nine 

 days in the specimens observed. Many (perhaps 10 or 15) others, 

 which I observed, died during that state. This was probably 

 partly due to the fact that they were handled too much, or 

 became too dry in the cages where they were kept, but I have 

 often found dead pupae under stones on banks of streams. 



The adults are perhaps as good fliers as Chauliodes, and both 

 of these will make longer flights th^in Sialis; both are often 

 found at great distance from streams, while Sialis seldom 



