THYSANURA 223 



coxites (Fig. 221). Compound eyes large and contiguous. Pro- 

 thorax smaller than the mesothorax. Middle and hind legs with 

 vStyli. Saltatorial insects. 



This family is represented by the genus Machilis, of which several 

 species occur in North America. These insects are found in heaps of 

 stones and in other concealed places; they are very active and leap 

 with agility when disturbed. They are about 12 mm. in length. 



Family 2, Lepismatidae. Abdominal tergites not covering the 

 sides of the coxites. Eyes small and distant. Prothorax as large 

 as or larger than the mesothorax. Middle and hind legs without 

 styli. Not saltatorial insects. 



The best-known representative of this family is the silverfish or 

 fish-moth Leptsma sacchanna (Fig. 228). It is silvery white with 

 a yellowish tinge about the antennas and legs and measures about 



Fig. 228. — Lepisma 

 saccharina. (After 

 Lubbock.) 



8 mm. in length. It is often a troublesome pest in laundries, li- 

 braries, and museums, as it injures starched clothes, the bindings of 

 books, labels, and other things on which paste or gkie is used. The 

 popular names were suggested by the clothing of scales with which 

 the body is covered. 



Another common representative of this family is the fire-brat, 

 Thermobia domcstica. This species resembles the fish-moth in 

 general appearance except that it has dusky markings on its upper 

 surface. It is remarkable for frequenting warm and even hot places 

 about ovens, ranges, and fireplaces. 



