178 



Elementary Principles of Agriculture 



thought. One species (Fig. 113) of ichneumon fly is 

 important because it attacks the green bug, usually in 

 sufficient numbers to prevent serious injury. This para- 

 site thrives only during warm weather, however, while 

 the green bugs may endure much cold weather. Below 

 central Texas, the parasitic flies are active at all seasons 

 and that section has never been seriously damaged by 

 the green bug. In other parts, the entire grain crops 

 have been almost destroyed several times because the 

 cool weather retarded the multiplication of the parasites. 

 Ichneumon flies are parasitized by other ichneumon 



flies, and these in turn 

 by others, reminding 

 one of the old adage 

 that " Large fleas have 

 smaller fleas to bite 

 'em." 



246. Ants. Many 

 species of ants live on 

 the eggs and larvae of 

 other insects. The "fire 

 ants" in particular are 

 very useful in cotton 

 fields because they de- 

 stroy many grubs of 

 boll -weevils in fallen 

 buds. The common red 

 stinging ant lives on 

 weed seeds and wild 

 grain, and sometimes 

 attacks other insects. 

 Some forms of ants, particularly some tropical species, 

 are serious pests. 



Fig. 114. Two common species of lady bugs. 

 a, hippodamia; 6. megilla; c and d, larva 

 stages. After Chittenden, United States 

 Department of Agriculture. 



