COLEOPTERA 



501 



pendages.and the structure of the caudal end of the body, afford useful 

 characters. The value of these characters in indicating the principal 

 divisions of the family is pointed out by Hyslop ('17)- 



An extended 

 series of experi- 

 ments were con- 

 ducted by Corn- 

 stock and Slin- 

 gerland ('91) in 

 an effort to discover a practicable 

 method of preventing the ravages 

 of wire-worms. In those species that 

 we bred, it required several years 

 for the larva to complete its growth. 

 In these species the full-grown larva 

 changes to a pupa in the latter part 

 of the summer, in a little cell in the 

 grotmd; the pupa soon afterwards 

 changes to an adult; but the adult 

 remains in the cell formed by the 

 larva till the following spring. 



Although we tried an extensive 

 series of experiments, extending over 

 several years, we were unable to find 

 any satisfactory way of destroying 

 the larvae infesting field crops. But 

 we fotmd that if the cells containing 

 pupae or recently-transformed adults 

 were broken, the insects perished. 

 We conclude, therefore, that much 

 can be done towards keeping these 

 insects in check by fall-ploughing; 

 for in this way many of the cells 

 containing pups 

 or yoimg adults 

 would be broken. 

 The eyed el- 

 ater, Alaus ocu- 

 latus .- Although 

 most of our click- 

 beetles are of 

 moderate size, 

 we have a few species that are large. The most 

 common of these is the eyed elater. This is the 

 great pepper-and-salt-colored fellow that has two 

 large, black, velvety, eye-like spots on the pro- 

 thorax (Fig. 597). These are not its eyes, how- 

 ever. The true eyes are situated one on each side 

 of the head near the base of the antenna. This 



Fig. 596. — A corn-plant growing in a 

 root-cage infested by wire-worms 

 and click-beetles. (From a speci- 

 men in the Cornell Insectary.) 



