4560. 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 increase 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 may be buried several inches in the ground. The 
