62 



The Simplest Insects 



causing it to loosen, and infests dry starchy foods. It runs swiftly and 

 avoids tiie light. It can be fought by sprinkling fresh 

 pyrethrum powder in bookcases, wardrobes, and 

 pantries. Another species, L. domestica (Fig. 93), 

 called the bake-house silverfish, is often common 

 about fire])laces and ovens, running over the hot 

 metal and bricks with surprising immunity from the 

 effects of the heat. This habit has gained for it in 

 England, according to Marlatt, the name of "fire- 

 brat." It can be distinguished from the species 

 saccharine by the presence of dark markings on the 



Fig. 92. — Japyx%\>.,iTom back. Both saccharina and domeslica are common 



CaUfornia. (Five times j„ Engj^nJ and saccharina lirobablv came to this 

 natural size.) " ' • 



country from there. 

 Machilis (Fig. 95) does not occur in houses, but is more common than 

 Lepisma outdoors. It is to be found under stones, in the soil around the 

 base of tree-trunks, among dead leaves and fallen pine-needles, and at least 

 one .species occurs in the sand of sea-beaches. 



Fig. 93. 



Fig. 94. 



Fig. 93.— The fish-moth, Lepisma domeslica. (.■Kfter Howard and Marlatt; a little 



larger than natural size.) 

 Fig. 94. — Young and adult of Lepisma sp., from California. (Twice natural size.) 



COLLEMBOLA. — The springtails, mostly of microscopic size, and wholly 

 unfamiliar to any but persistent explorers of nature, comprise many more 

 species than the Thysanura. Their most distinctive character is the pos- 

 session, by most of them, of the forked spring (Figs. 96 and 97), by 

 means of which they leap vigorously when disturbed. This spring is 



