62 
The Simplest Insects 
causing it to loosen, and infests dry starchy foods. It runs swiftly and 
avoids the 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 fireplaces 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 
saccharina by the presence of dark markings on the 
Fig. 92. —Japyx sp., from back. Both saccharina and domestica are common 
natura^size / FlVe times i n England, and saccharina probably came to this 
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 domestica. (After 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 
