152 



THE STUDY OF INSECTS 



Fig. 260. 



Pacific Coast, where they are found under stones and pieces 

 of wood lying on the gr< lund. They are apt to congregate in 

 large numbers under a single shelter, and are clumsy in 

 their movements. They defend themselves when dis- 

 turbed by elevating the hinder part of the body and 

 discharging an oily fluid from it. They present an 

 absurd appearance, walking off clumsily, and carry- 

 ing the hind end of the body as high as possible. 

 The most common species are large, smooth, club- 

 shaped beetles (Fig. 260), and are commonly known 

 as pinacate-bugs. These beetles and those belonging 

 to several closely allied genera lack hind wings. 



Family Cucujid^e 

 The Cucujids 



The insects of this family are very flat and usually of an elongate 

 form; most of the species are brown, but some are of a bright red color. 

 As a rule they are found under bark and are believed to be carnivorous 

 both in the larval and adult states; but some feed in grain. There are 

 nearly one hundred species in our fauna. 



The most important member of this family is the corn silvanus, 

 Oryzaphilus sur in amen sis, which is one of the small beetles that infest 

 stored grain. This species is readily distinguished from other small 

 beetles with similar habits by its flattened form and the saw-like edges 

 of the prothorax. Besides grain it often infests dried fruits and other 

 stores. It measures from -^ to \ of an inch in length. The larva as well 

 as the adult feeds on grain. It differs from the larva of the granary- 

 weevil (Sitophihts) in the more elongate form of its body and in the 

 possession of three pairs of legs. 



Family Coccinellid^e 



The Lady-bugs 



These insects are well-known to nearly everyone under the popular 

 name given above. They are more or less nearly hemispherical, generally 

 red or yellow, with black spots, or black, with white, red, or yel- 

 low spots. 



The larva? occur running about on foliage; they are of- 

 ten spotted, with bright colors and clothed with warts or 

 with spines (Fig. 261). When ready to change to a pupa the 

 larva fastens itself by its tail to any convenient object, and 

 the skin splits open on the back. Sometimes the pupa 

 state is passed within this split skin, and sometimes the skin is 

 forced back and remains in a little wad about the tail (Fig. 

 262). 



With very few exceptions, the lady-bugs are predacious, 

 both in the larval and adult states. They feed upon small 

 insects and upon the eggs of larger species. The larva? of certain species 



Fig. 261. 



Fig. 262. 



