222 PRODUCTIVE FARMING 



There are certain parasitic insects living on the more 

 injurious forms and this aids materially in the control of 

 insect pests. (See Figs. 140, 141.) 



Exercise. — Parasites of Insects. — In the breeding cages 

 or in the boxes where cocoons are kept, watch carefully for 

 the indications of parasites. Some of them may be similar 

 to one or more figures in this chapter. 



Birds as Insect Destroyers. — Many kinds of birds are 

 great friends to the farmer and his crops, because of the great 

 numbers of noxious insects which they destroy. Some birds 



Fig. 139. — 15-spotted lady-beetle: a, larva; h, pupa; d-g, adult varieties. (From 

 Smith's "Insect Friends and Enemies.") 



do harm at one season by eating fruits or grain, but they com- 

 pensate for it at other times by eating insect pests. The 

 majority of the land birds eat insects at all times; but during 

 the nesting season their food is largely composed of insects. 

 Exercise. — Common Birds. — The members of the class 

 should name and briefly describe the birds that they know. 

 Have the food-habits of these coromonest birds reported by 

 some one. United States Farmers^ Bulletin 54, '^Some 

 Common Birds in Their Relation to Agriculture,'' will be 

 very helpful. Considerable interest should be taken in the 

 protection of insect destroyers. 



