The May-Flies or Shad-Flies 



to be poisonous to the larv^. After the eggs hatch the larvae live 

 upon mud or the small vegetation which grows on stones and 

 the stems of large water-plants. Some of them are apparently 

 predaceous. They cast their skins several times during the tirst 

 few days after their birth. ^ u ** 



These larvae, or nymphs, as all of the early stages of the May- 

 flies are called, are very important fish food. Forbes has found 

 them to be the most important food of the white bass, the 

 toothed herring, the shovel-fish and the croppies, while the rock 

 bass, the common perch, the striped bass, the darters, the cat- 

 fish the suckers, and many other freshwater fish feed upon them 

 very largely. The writer has been appealed to quite recently on 

 the subject of the possible extermination of these insects along 

 the St. Lawrence River, where they cause so much annoyance 

 by their swarming flight, but their value as food for fish would 

 make such an extermination extremely undesirable. The St. 

 Lawrence is noted for its fine fish and the fishing possibilities 

 attract so many summer visitors to its shores that the tern- 

 porary annoyance of the shad-flies should joyfully be borne. 



The larval life is a long one, lasting from one to three years, 

 and the number of molts is very large. There may be as many 

 as twenty. The adults, as well as the larvse, are favorite fish 

 food Of the swarms that issue, many meet their ultimate rest- 

 ing place in the water, or more strictly speaking, in the stomachs 

 of fishes Fishes are so well acquainted with them that imita- 

 tion shad-flies afford the best bait in certain regions. In England 

 the so-called flies known as duns, drakes, and spinners are all 

 imitations of Ephemerids. Although so enormously numerous in 

 individuals, the Ephemerida is not a large group in number of 

 species, and only about three hundred have been described. 

 There must be very many more, however, and possibly the ditti- 

 culty with which these insects are preserved in collectioris 

 accounts for the fact that comparatively few have been named. 

 If pinned they shrivel up and dry into such queer shapes that 

 the coloration and structural characters become obscure. Good 

 aquarium studies for any of our North American species will be 

 found to be interesting and will be of valuable record. 



A very good table for determining the nymphs of May-flies 

 has been prepared by Needham, and will be found in Bulletin 48 of 

 the New York State Museum of Natural History. Albany, 1901. 



379 



