COLLECTING 



183 



Fig. 65. — A screen with handles, 

 for use in riffle. A piece of window 

 screen wire cloth 1x2 feet, with 

 edges "hemmed," ends inserted in 

 saw groove cut in handles and nailed 

 fast there. 



midge larvae and other animals, 

 not insects (such as craw-fishes 

 and little white mussels) and the 

 way to get them is by scraping up 

 the bottom stuff in a sieve net, 

 sifting it and picking them out. 

 Where loose bottom trash occurs, 

 they may be gotten with a 

 common garden rake by raking the 

 trash ashore and then picking it 

 over. 



10. The rapids of the brook will 

 furnish stonefly and mayfly nymphs, hellgrammites and 

 fish fly larvae, flat "water pennies" and other larvae of 

 riffle beetles, midge and cranefly larvae, etc., and the way to 

 get them is to hold a screen in the current, stir the stuff on the 

 bottom, upstream side, to dislodge them, and as soon as 

 they are gathered on the screen, lift it and pick them off. 



Some general suggestions. — Aquatic insects are best 

 gathered at times of low water when they are more con- 

 centrated in the contracted water areas. This is of less 

 consequence in steep banked ponds and in small spring-fed 

 streams; but larger open streams after a flood will often seem 

 to be entirely "washed out"; and in very shallow newly 

 filled ponds many of the shore animals will be for a time out 

 in deeper water. 



Collect in quantities when the collecting is good. Collect 

 when you find the insects swarming, as do mayflies, midges 



