THE MAY-FLIES OR SHAD-FLIES 



(Order Ephemerida.) 



The so-called May-flies, or shad-flies, are the insects which 

 constitute this order. They are known by one name or the 

 other by almost every one who has seen them swarming about 

 the electric lights during the summer or who lives in the vicinity 

 of some large watercourse in which these insects breed in in- 

 calculable numbers. Structurally speaking, the adult insects are 

 very interesting creatures. They are distinguished from other 

 insects by their short antennae, their extremely large front wings 

 as compared with the very small hind wings, the absolutely 

 atrophied mouth-parts and the long, slender filaments, two or 

 three in number, at the end of the abdomen. The transformations 

 are complete and the early stages are always passed in the water. 



The larva; are active creatures with long, strong legs, and 

 breathe by means of tracheal gills. They both swim and 

 crawl and feed very largely upon vegetable matter, diatoms and 

 confervse being found in their stomachs. They may be found 

 under stones in running streams or swimming among water 

 plants in quiet waters, or they may live at the bottom more or 

 less covered with slime or mud. Some forms burrow into the 

 sand-banks of rivers. The pupa or nymph is also active and 

 feeds. It has small wing pads, and, when ready to transform, it 

 floats upon the water, and the skin of the back opens and the 

 winged insect flies out. The emergence is extremely rapid and 

 the insect flies away almost immediately after the skin cracks. 

 A very curious phenomenon occurs with these insects which is not 

 found with any other insect, and that is that there is a molt after the 

 fly issues from the nymph. It flies away to the shores in the con- 

 dition called the sub-imago stage and again the skin splits and the 

 true-imago, or adult, issues. This shedding of the sub-imago skin 

 is said sometimes to take place while the insect is flying in the air. 



The life of the adult is short; in fact, these insects were 

 named after the Ephemerides of the Greek mythology, creatures 

 which lived but a day, and from this root comes our common 



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