Economic Importance of Animals 555 



Certain species are used as food by savages and Orientals. The green- 

 ish katydids feed on leaves and tender plants, while they occasionally 

 attack other insects. Their characteristic chirping in the evening is a 

 source of amusement and joy unless it should become excessive and 

 disharmonic. The long-horned or meadow grasshoppers consume large 

 quantities of vegetation of the fields, including grains and grasses. 

 Grasshoppers may destroy entire fields of crops, particularly in the 

 West and South. The house cricket (Fig. 282) or true cricket produces 

 the characteristic chirping and feeds principally on plants, although 

 they may attack clothing. The mole cricket burrows in the ground and 

 attacks plants, especially potatoes. The striped tree cricket attacks 

 berry plants, grapevines, and other plants. 



Fig. 281. Fig. 282. 



Fig. 281. — A common household cockroach of the order Orthoptera. 

 Fig. 282. — A common cricket of the order Orthoptera (class Insecta). 



Order 9 — Isoptera: The termites (Fig. 283) are social insects living 

 in colonies. Originally they were abundant only in the tropics, but in re- 

 cent years they have become a serious pest in the United States where 

 they greatly damage structures which are made of wood. They live in 

 dark places and may not be noticed by the untrained except during their 

 so-called swarming periods. At other times they are usually unnoticed, 

 which may lead one to believe they are not present. They may build 

 earthen tunnels and pass through them out of sight. The colonies of 

 certain species are underground in order to secure moisture and to pre- 

 vent freezing in cold weather. They usually destroy only the inner parts 

 of woods and rarely come to the surface, thus betraying their presence 

 and great destruction. Sometimes, only the outer shell of a wooden 



