FARM METHODS FOR THE CONTROL OF INSECTS 39 



as larvae; the cotton boll worm or corn ear- worm hibernates 

 in the pupal stage; while May beetles and click beetles hibernate 

 as newly transformed beetles; but all of them will be similarly 

 affected by the breaking up of their winter cells, which is the 

 most effective manner of combating them. 



Other insects lay their eggs in the ground in the fall which 

 may be buried too deep for the young to emerge, or larvae or pupae 

 which normally remain near the surface may be turned under so 

 deeply as to destroy them. Thus grasshopper's eggs are laid in 

 the fall just beneath the surface, and by plowing in late fall or 

 early spring they may be turned under so that but few are able to 

 emerge, which is the best means of combating them. The apple 

 maggot hibernates in the pupal stage just beneath the surface of 

 the soil, and by deep plowing in early spring the puparia may be 

 buried too deeply for the flies to emerge. 



Young grasshoppers are often destroyed after they hatch by 

 plowing deep furrows, starting at the outside of the field and plow- 

 ing in a square, thus forcing them to the centre and catching large 

 numbers of them in the furrows. 



Early plowing and thorough harrowing in the spring are of 

 value against cutworms by keeping the ground fallow and thus 

 starving them out before a crop is planted and the same method 

 may be used against other pests with similar habits. 



Thorough cultivation in the summer has been found to be of 

 value against many insects, affecting them differently according to 

 their habits. Many which pupate in the soil during the summer 

 are destroyed while making their pupal cells, or these cells are 

 broken and they are thus subject to abnormal moisture and tem- 

 perature conditions and are thus killed. This has been shown to be 

 the case with the cotton bollworm or corn ear-worm, and is true 

 of the plum curculio, against which thorough cultivation has 

 proved to be one of the most effective means of control in apple 

 orchards. Thorough cultivation is also of importance in breaking 

 up the nests of ants which care for such aphides as the corn root- 

 aphis. Summer fallowing is used to starve out some pests; for 

 example, the clover root-borer may be eradicated by plowing up 



