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May-flies or Shad-flies — Part 2

These larvae, or nymphs, as all of the early stages of the Mayflies 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 catfish, 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 temporary 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 larvae, are favorite fish food. Of the swarms that issue, many meet their ultimate resting place in the water, or more strictly speaking, in the stomachs of fishes. Fishes are so well acquainted with them that imitation 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 difficulty with which these insects are preserved in collections 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.