WELCH J WATER IX SECTS 191 



matter to watch the development of the different stages in the Ufe 

 of this insect and to become famihar with the habits of each. 



The Stone Fly Nymphs (Fig. 16). 



The larval form of this insect is found only in rapid streams, 

 being most abundant in rapids and riffles where the water rushes 

 over half submerged rocks. They may be found at almost any 

 time during the collecting season. Lift submerged stones sud- 

 denly and look carefully on the lower side. There will often be 

 found clinging to the rock a flat larva, near ^ inch long, with 

 two long bristle-like antennae, two long bristle-like structures at 

 the end of the abdomen, and with tufts of branching gills at the 

 bases of the legs. The legs are usually fringed with hairs. They 

 are very active and quickly hide themselves when disturbed. To 

 collect them, lift up stones in rapids and turn over quickly and 

 then pick off the nymphs or wash them off into a jar. They 

 cannot live except in running water, and in order to rear them, 

 push one of the out door cages down over the rock under which 

 some of these nymphs are living — and then w-atch results. The 

 full grown insect is ^ to 2 inches in length, often grayish in color, 

 has four large, many-veined wings of which the hind ones are the 

 larger. When at rest, the fore wings lie flat on the back cover- 

 ing the much- folded hind wings. These adults can be found near 

 the rocky streams where their larvae live, resting on rocks, roots, 

 trunks of trees and the green foliage. 



May Fly Nymphs (Fig. 17). 



These nymphs can usually be found in abundance in every 

 sort of fresh water situation and at almost any time during the 

 Spring and Summer. They crawl about on the bottom among 

 the submerged trash or cling to the submerged parts of water 

 plants. The full grown insects are those feeble, frail-bodied, 

 gauzy- winged creatures with long bristles at the tip of the abdo- 

 men which often suddenly appear near the shores in such count- 

 less numbers and then as suddenly disappear. This appearance 

 usually occurs at the beginning of twilight, and their flying whirl- 

 ing dance is an interesting sight. The mating takes place during 

 this dance and the eggs are dropped to the surface of the water 

 soon after. The adults take no food and usually live but a few- 

 hours. They are attracted to light and millions of the dead ones 

 may sometimes be found under a single arc light of a river or 

 lake town. Collect the nymphs by sweeping the bottom and the 

 water plants. Put them into a small aquarium containing a little 

 mud and feed them on water fleas or small water insects. 



