110 



SCHOOL ENTOMOLOGY 



in great numbers. 

 Some of the ground- 

 beetles are distinctly 

 valuable as destroyers 

 of injurious caterpil- 

 lars, notably, those of 

 the gypsy-moth. In 

 numbers of species the 

 ground-beetles are near 

 the head of the list, 

 there being about a 

 thousand from the 

 United States. 



67. Aquatic Beetles. 

 There are three com- 

 mon families of beetles 

 that are aquatic in 

 habit.' They may be 

 recognized by their 

 regular oval outlines, 

 their legs fitted for 

 swimming, and the 

 uniformly dark colors, 

 as well as by the habi- 

 tat. The Whirligig- 

 beetles (Gyrinidce) , are 



FIG. 79. Types of Beetles. 

 Slightly reduced. 



Upper row , Tiger-beetles 

 (Cicindelidce) ; next two TOWS, 

 Aquatic forms (Hydrophilidce, 

 Gyrinida;, and Dytiscidce) ; fourth 

 row, Carrion beetles, (Silphidoe) ; 

 fifth row, Staphylinidce; sixth 

 row, Lady-bug beetles and larva 

 (Coccinellidce) ; lower row, left, 

 Ptinidce; center, Erotylidce; right, 

 Larder beetle (Dermestidce), 



