FIELD BOOK OF INSECTS. 



Frequently the surface of still pools is 

 covered by a mass of tiny dark specks of 

 insects which spring about, when disturbed, without even 

 denting the surface film. Sometimes similar creatures 

 are seen on the snow during bright spring days, becoming 

 a nuisance in maple-sugar camps by getting into the sap. 

 These are Collembola or Spring-tailsgrotesque-looking 

 creatures which, when at rest, keep the "tail" curved 

 under them and jump by straightening out. See Smin- 

 thurus aquaticus in Plate VIII. 



PLECTOPTERA; EPHEMERID^E 



The family name of May-flies (see Plate VIII) comes 

 from the same Greek root as does "ephemeral" and, 

 although the term would fit the adult lives of most insects, 

 it does forcibly apply to many of these, the three-weeks 

 winged life of Chloeon dipterum being exceptional. How- 

 ever, though the winged stage may last but a day or, 

 better, a night their lives from egg to adult are, insectly 

 speaking, among the longest, some taking three years for 

 their development. A female drops two packages, each 

 of which may contain several hundred eggs, into the water; 

 the packages break almost immediately and, after some 

 time, there hatch from the eggs larva? with gills along each 

 side of the abdomen and three (as a rule) tail filaments. 

 According to the species, these larva? may swim rather 

 freely, or make burrows in the mud, not swimming at 

 a ll f or the sort you are most likely to notice crawl 

 about on the under side of submerged stones. Some 

 feed on vegetable matter; others are carnivorous. These 

 larvse molt frequently, twenty times having been recorded 

 for one species, but the chief change is the gradual appear- 

 ance of wing pads. The young of insects having, as these 

 do, incomplete metamorphosis are usually called nymphs 

 instead of larvae, although this term is sometimes re- 

 stricted to the stages in which the wing pads are quite 

 evident. The full-grown nymphs crawl out of the water, 

 frequently in crowds; the skin splits down the back of 

 each and the freed creatures make short flights. But 

 molting is not over yet. Nature loves exceptions, perhaps 



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