456 NEW YORK STATE MUSEUM 



with the long caudal breathing- tubes have been found only in 

 stagnant or quiet water. 



The larvae are carnivorous, and do their feeding chiefly in 

 the dark. The large larvae readily eat smaller ones of their 

 own species, and larvae of Sialis, caddis worms, small dipterous 

 larvae, and other accessible forms with soft bodies. Weed 

 [1889] says that a larva in an aquarium ate Notonecta 

 undulata, house flies, and a spider. 



The length of the larval period has not been definitely deter- 

 mined. It may be judged from the data already known that it 

 is about three years. The amount of increaise at each molt, if 

 found from a number of examples, would furnish data for deter- 

 mining the number of molts. The number of molts compared 

 with the average time between molts would determine rather 

 closely the larval period. The great difficulty in the way of 

 determining the number and average time of the molts, is that 

 they can not easily be cared for and fed in their exact natural 

 conditions through a long period and their increase at each 

 molt carefully measured. Larvae if fed well will doubtless molt 

 more rapidly than those which are poorly fed. I kept larvae 

 alive in running water from Sep. 2, 1899, to June 1, 1900. Only 

 two of them molted during that period, but they were very 

 poorly fed. 



Young larvae which hatched June 15 to 20, 1899, over a quiet 

 part of a brook where the bottom was a large, flat rock deeply 

 covered with sediment, were found in great numbers and of 

 nearly uniform size four months later, at the close of the warm 

 season. It is from these and from the range of sizes observed 

 at one place as the result of one day's collecting, that I have 

 thought the larval period must be about three years. 



When fully fed and of proper age, the larva leaves the water, 

 makes a cell in rotten wood, in the earth, or under a stone or 

 even in mud, where it sheds the last larval skin to assume the 

 pupal form. 



The pupae are difficult to find, as they are often far from 

 water and mav be buried several inches in the ground. The 



