184 INSECTS AFFECTING VEGETATION 



rial left as possible for protection of the insects. Cultivated meadows 

 may be safely burned over when the ground is frozen without injury 

 to the grass. 



If a system of rotation could be adopted which would entirely 

 disassociate small grains from corn, very little damage from the 

 chinch bug would ever be experienced, at least to the latter crop. 

 Following out this idea would mean the planting of a farm to corn 

 one year and to wheat and small grains the next or some similar sys- 

 tem of rotation. 



In checking the midsummer migrating bugs some good may 

 also be done by turning under the first rows of corn or other crop at- 

 tacked. To have any practical value, however, the plowing must be 

 done very deeply, or many of the bugs will escape. 



The making of protecting furrows, as recommended for the 

 army worm, is also applicable to the chinch bug. The bugs which 

 collect in the furrow may be killed either by dragging a log along or 

 by thoroughly wetting with the kerosene and water mixture. 



A good deal of effort has been made in some places to protect 

 fields by placing about them lines or barriers of coal tar. Where this 

 is done the line of tar must be renewed several times a day. At in- 

 tervals along it holes may be bored, in which the bugs will accumu- 

 late and may be destroyed. All that is necessary is to put a single 

 straight line of tar in front of the migrating bugs and make holes 

 on the side of attack with a post auger at distances of 8 or 10 feet 

 close to the tarred line. Various other forms of barriers will easily 

 suggest themselves, such as putting a line of boards about a field and 

 smearing it with tar or combining the tar with the furrow method. 

 Promptness and vigilance are the essentials in any of these remedial 

 operations. 



Summing up the subject of preventives and remedies, it may be 

 said that the ones of real value are the clearing of farms and adjacent 

 lands of rubbish and deadened grass by burning, the adoption of a 

 rotation of crops which will separate the small grains from the later- 

 ripening crops such as corn and late-sown millet, and the adoption 

 of the steps indicated to stop the migrating midsummer hordes. 



The Hessian Fly. The Hessian fly is one of the principal ene- 

 mies of the wheat crop, the minimum annual damage due to it being 

 estimated at about 10 per cent of the product in the chief wheat- 

 growing sections of this country, which indicates an annual loss of 

 40,000,000 bushels and over. An injury of from 50 per cent to a 

 total failure of the crop is not infrequent in certain localities, and the 

 resulting loss is proportionately greater. 



The parent insect is a very fragile, dark-colored gnat or midge, 

 about Ys inch long and resembling somewhat closely a small mos- 

 quito. As commonly observed, however, more or less hidden in the 

 base of young wheat plants or other small grains, the insect appears 

 either in the form of a footless maggot, or larva, or in what is known 

 as the flaxseed state, which corresponds to the chrysalis of other in- 

 sects. The injury to the plant is done altogether by the larva, which 



