64 



The Simplest Insects 



is dull black, with liead, legs, and bases of the antennae rust-color." Sniyn- 

 thurus aquaticus (Fig. 87) often occurs in great numbers on the surface of 

 pools. The insects look like tiny black spots on the water surface, but a 



little observation soon reveals their 

 lively character. 



The Podurida; and Entomobryidae 

 are represented in North America by 

 twelve and fourteen genera respec- 

 tively. Many of the Podurids are 

 covered with scales and are often 

 prettily colored and patterned. The 

 scales (Fig. 98) are very minute and 

 bear many fine lines and cross-lines, 

 regularly arranged. On this account 

 Fig. 98. Fig. 99. thev are much used as test objects 



Fig o8.-Scak-s from a springtail. (.Vfter j^j.' microscopes, the quality of the 



Murray; greatly niagniticd.) "^ . ^ . •' 



Fig. q9. — The snow-tli-a, Achorutes nivicola. lens being determined by its capacity 

 (.\fter Folsom; much enlarged.) ^^ rg^,g,^i i^eir extremely fine mark- 



ings. One of the most interesting Podurids is 

 the snow-flea, Achorutes nivicola (Fig. 99), which 

 gathers in large numbers on the surface of snow 

 in the late spring. Comstock says that the 

 snow-flea is sometimes a pest where maple- 

 sugar is made, the insects collecting in large 

 quantities in the sap. 



An interesting representative of the Entomo- 

 brv'idae is the house springtail, Lepidocyrtus ameri- 

 canus (Fig. 100), said by Marlatt to be "not 

 infrequently found in dwellings in Washington." 

 It is about one-tenth of an inch long, silvery 

 gray, with purple or violet markings. In Europe 

 also one species of .springtail is common in 

 houses. As these insects live on decaying vege- 

 table matter, they probably do no special harm 

 in the house. They especially frequent rather moist places, and may often 

 be found in window-plant boxes and conservatories. 



Fig. 100. — The American 

 springtail, Lepidocyrtus 

 americanus, ventral aspect, 

 showing spring folded un- 

 derneath body. (After 

 Howard and Marlatt ; 

 much enlarged.) 



