152 FARM FRIENDS AND FARM FOES 



be comparatively little injured by birds. All of them, how- 

 ever, '^re easily destroyed by sprapng with arsenical poisons 

 or even with insect powder or hellebore. 



Four-winged Gallflies 



The next most important group of injurious insects be- 

 longing to the Hymenoptera is that of the Gallflies (Cyni- 

 pidae). There are many species of these insects which 

 affect almost every sort of tree, shrub, and herbaceous 

 plant, but comparatively few of them are destructive to 

 cultivated crops. 



One of the most familiar of these injurious insects is the 

 species that makes its home in' blackberry canes, causing a 

 large abnormal swelling upon the cane which is commonly 

 called the pithy Blackberry Gall. The small four-winged 

 Gallfly deposits its eggs in the growing stem, a large 

 number of eggs being placed near together. These hatch 

 into tiny larvae which bring about an abnormal growth of 

 the blackberry tissues that eventually takes the form of the 

 curious gall. If you cut one of these open, you are likely 

 to find a great many little cells in which the lan^ae are 

 living. They finally transform to pupae within these cells, 

 and emerge later as adult flies. The cuttmg and burning 

 of all affected stalks in winter will help to check the increase 

 of these insects. 



A great many forms of Gall insects may be found at al- 

 most any time upon the willows and the oaks. The familiar 

 oak apples are excellent examples of the sort of abnormal 

 vegetation growth caused by the Gallflies. 



Chalcid Flies 

 The great family of small parasitic flies, called the Chalcid 

 family, consists for the most part of insects that live in their 



