OTHER ENEMIES OF MAN 



225 



of rats that can live and reduces the breeding of rats. 

 Hunger also makes trapping and poisoning more ef- 

 fective. Foodstuffs should be kept in rat-proof build- 

 ings and containers, and waste and garbage should be 

 kept in tightly covered garbage cans. The uncovered 

 garbage can is one of the common sources of food 

 supply for rats. 



How is plant life affected by insect pests? Only a 

 few people are aware of the tremendous financial loss 

 to people of the United States caused by insect ene- 

 mies of plant life. Every kind of plant raised by the 

 farmer, every kind of fruit tree, and every kind of 

 forest and shade tree is subject to attacks by destruc- 



Courtcsy U. S. Department of Agriculture 



FIG. 355. FEEDING PLACES OF RATS 



tive insects. Recently experts of the United States 

 Department of Agriculture estimated the annual loss 

 in the United States due to injurious insects, as fol- 

 lows: 



Farm crops 



Cereals $ 430,204,600 



Hay 116,230,500 



Cotton 165,000,000 



Tobacco 16,900,800 



Vegetables 199,412,600 



Sugar crops 8,436,800 



Fruits 141,264,300 



Farm-forest products 22,138,900 



Other crops 29,649,700 



Total $1,129,238,200 



Natural forests and forest products $ 100,000,000 



Products in storage 100,000,000 



Insect-borne diseases of man 150,000,000 



Direct or indirect damage to domestic animals 100,000,000 



Insects exist in greater variety and abundance than 

 any other sort of animal life. Not all are injurious, 

 however, and some have considerable commercial 

 value. Unfortunately thousands of them infest plants. 



Mexican be an btl 



Chinch bug 



Size 



B\acV carpet beetle 



Corn root a.pK\dL 



Hessian i\y 



Cabbage Butterfly - &ctuai s'n.e 



OLCtUdll 



> size 



**"** Europe Corn Borer 



<iciuo.l size 

 Gypsy Moth 



Case 



actual sue 

 Grasshopper 



<SX.tuaA 317. e 



PoVaVo beetle 



Grand total . , $1,579,238,200 



Japanese beetle 



FIG. 356. INJURIOUS INSECTS 



Some plants have as many as two hundred different 

 kinds of insect enemies, but usually only a few of 

 them are very destructive. Pictures of some of the 

 most common insects injurious to vegetation are 

 shown in Figure 356. If you are interested in the life 

 histories of any particular ones, consult special refer- 

 ences listed at the end of the topic. 



In addition to native insect pests we must contend 

 with certain introduced species. Some years ago the 

 European gypsy moth and browntail moth became 

 established here and destroyed many of the trees of 

 New England. Already more than eight million dollars 

 have been spent to hold this pest in check. The Euro- 



