BULLETIN 39, UNITED STATES NATIONAL MUSEUM. 



M 



Even where the bottom of the pond seems bare, the rake will bring 

 ashore much loose mud and silted material, containing the burrowing 

 nymphs of dragon flies and may flies ( Gomphus, Heocagenia, etc.) ; but, for 

 collecting in such places, the sieve net shown in fig. 1 is much better. 

 This is a net and a sieve combined. It has a long handle, and is so 

 shai^ed that it can be easily used from the bank. The frame is of light 



Fig. 1. — Sieve net for collecting nymphs from sand and mud. 



steel rods; the sides are of galvanized iron; the bottom is of galvanized 

 wire screen. It is especially adapted for scraping up from the bottom 

 mud, fine silt, and sand, and for sifting out at the surface the nymphs 

 therein contained. It may be used away from shore where a rake is 

 almost useless, and it is much better than a rake for collecting burrow- 

 ing nymphs (for which it was devised), but it is not so good as a rake 

 where there is much material. 



2. Forms living above the bottom in still or slowly floicing water. — The 

 more agile nymiDhs of dragon flies and mayflies are exceedingly abun- 

 dant, clambering among the submerged branches of erect aquatic 

 plants. All but a few of the smallest species are easily taken by 

 "sweeping" the plants with any of the well-known forms of water net. 

 There are, however, a few little nymphs of may flies 

 that can hardly be dislodged with the net, and that 

 are hardly discoverable on plants withdrawn from 

 the water. These may be found by examining the 

 plant stems, a small bunch at a time, in a white 

 dish of clean water. 



3. Forms living in the rapids of streams. — Many 

 of these may be obtained by simply picking them 

 by hand from stones lifted out of the stream, but 

 not all. Those which cling to swaying sedge and 

 willow stems may be "swept" with a water net; 

 but a net better adapted for collecting in rapids is 

 shown in fig. 2. It consists of a ring of stout spring 

 wire 3 to 4 feet in diameter, to which is attached 

 a very shallow bag of coarse bobinet, and at one 

 side is a handle only long enough to be held readily. 

 It is intended to catch insects adrift in the stream, 

 and is accompanied by an instrument for dislodging them. Such an 

 instrument is figured at the right of the net. It consists of a handle 



FiQ. 2.— Sag net, hook, and 

 brush for collecting in 

 rapids. 



