302 



ELEMENTABY STUDIES IN INSECT LIFE 



before the last of September. Now, if the summer 

 volunteer wheat is kept under, and wheat, rye and 

 barley sowing is postponed until after the middle of 

 September, it is evident that, since the Hessian fly 

 can live only on these cereals, the young of the fall 

 brood will not find proper nourishment. 



Clean culture is everywhere and at all times to be 

 commended, since rubbish of any kind and all kinds 

 offers a refuge for the hibernation of insects, and weeds 

 furnish nourishment for the growing insects. The fol- 

 lowing illustrates the point: crab-grass had been al- 

 lowed to grow undisturbed through the summer in a 

 young pear orchard. The crab-grass was plowed under 

 in October. The leaf-eating insects, driven from the 

 crab-grass, defoliated the young pear trees. These be- 

 gan to bud again, when a heavy frost occurred, biting 

 the tender buds and killing many of the trees. 



Preventives. Clean, thorough culture. Bands of 

 cotton are placed around the bases of trees, then cov- 

 ered with tar or similar harmless adhesive substances. 

 This is done to prevent the ascent of climbing cut- 

 worms, canker-worms, or the wingless female parent 

 of the canker-worm. Ditching, with occasional post- 

 holes in the ditch, for army-worms and chinch-bugs. 

 (See page 136.) 



Rotation of Crops. Crop rotation is very effective. 

 The corn-root worm rarely effects serious damage until 

 land has been planted in corn at least three years suc- 

 cessively. As before stated, the best means of preven- 

 tion is thorough and clean culture. When insects be- 

 come destructive they should be reckoned as a factor 

 in deciding proper modes of cultivation. 



