INSECT PARASITES AND PREDATORS OF INSECT PESTS 



17 



In recent years efforts have been made to extend the usefulness 

 of this parasite by rearing the species in enormous numbers upon 

 grain moth eggs and liberating them in the infested fields and 

 orchards early in the season. This has been tried on a number of 

 important pests of field crops and orchard trees, but the results thus 

 far have not been conclusive. This work is still in the experimental 

 stage, and at present it is not recommended to growers as a field 

 practice. 



In addition to Trichogramma, many other species of minute wasps 

 parasitize the eggs of moths, butterflies, beetles, and plant bugs. 

 Two species, which attack the eggs of the gypsy moth, have been 



Figure 12. — A, Several species of ground beetles of the genus Calosoma, about natural 

 size ; B, a typical ground beetle larva, enlarged about three times. 



imported from Japan and one of them also from Europe, and are 

 now well established in this country. ■ 



GENERAL INSECT FEEDERS 



There is a wide variety of insects which, in either the larval or adult 

 stage, have the habit of feeding upon such soft-bodied insects as they 

 may encounter. Among these are the ground beetles, the tiger beetles, 

 the robber flies, and a number of common plant bugs. 



The ground beetles of the family Carabidae (fig. 12) and their 

 larvae feed upon many kinds of insects. The adult beetles are found 

 mainly upon the surface of the ground, though some climb trees; 

 the larvae are generally found either in the soil or beneath rubbish, 

 but a few of these also climb trees in search of their prey. 



