De 



1958 



Decker: Economic Entomology 



123 



percentage of the fruit infested since the 

 establishment of the parasite is less than 

 one-tenth what it was before colonization 

 of the parasite was initiated. 



Shortly after the European corn borer 

 made its appearance in the Midwest, at- 

 tempts to introduce several of its parasites 

 into the infested area (1926-1930) were 

 relatively, if not wholly, unsuccessful. 

 Later attempts, in which the Illinois Nat- 

 ural History Survey and the United 

 States Department of Agriculture co-op- 

 erated (1944—1950), were more success- 

 ful, and a Tachinid fly, Lydella stabiilans 

 grisescens , became firmly established in 

 all sections of the state. Surveys made 

 annually for the past 10 years have shown 

 that, for the state as a whole, 15 to 40 

 per cent of the overwintering corn borers 

 are parasitized and destroyed by this fly. 

 In many instances parasitism in some of 

 the northern Illinois counties has run as 

 high as 80 to 85 per cent. While this 

 parasitic fly has not eliminated the corn 

 borer, it plays a very important role in 

 holding this pest in check. 



VALUE OF INSECT CONTROL 



Man's progress in applied entomology 

 is partly obscured by the ever-changing 

 circumstances and conditions of insect 

 control. Quantitative data on the exact 

 magnitude of insect damage are generally 

 unavailable, and only the more or less 

 catastrophic insect outbreaks are ade- 

 quately recorded in the literature. There 

 are few specific points of reference with 

 which we can compare the present with 

 the past. Our memories are often faulty. 

 We recall that Grandfather had a home 

 orchard and how much we enjoyed the 

 fruit; only after prolonged meditation do 

 we also recall that only 1 apple in 10 was 

 fit for storage in the fall, and that even in 

 preparing a pie from the stored apples 

 Grandmother had to cut out numerous 

 areas damaged by codling moth. 



Despite the paucity of precise quanti- 

 tative data, entomologists have developed 

 practical control measures for a long list 

 of once serious pests. Orchardists are 

 now able to produce fruit crops 90 to 99 

 per cent free of insect damage instead of 

 crops only 10 to 50 per cent free of in- 

 sect damage, as they were 100 years ago 



or as they are now in abandoned or un- 

 sprayed orchards. The Colorado potato 

 beetle, which came close to eliminating 

 Irish potato production just about 100 



Table 1. — Number of acres treated with 

 insecticides and estimated profit from treat- 

 ment for a few important insect pests of 

 cereal and forage crops in Illinois, 1953-1957. 



Number of Number of Estimated 



Year Pest Species Acres Profit From 



Considered* Treated Treatment 



*Insects considered in these surveys: spittlebug, leaf- 

 hopper, spotted alfalfa aphid, sweet clover weevil, pea 

 aphid, soil insects, chinch bug, cutworms, grasshoppers, 

 European corn borer, and fall armyvvorm. 



years ago, is no longer regarded as a seri- 

 ous pest. The grasshoppers, the army- 

 worms, and the chinch bug, which less 

 than a century ago caused many Midwest- 

 ern pioneers to give up in despair and to 

 abandon their farms, can now be con- 

 trolled with comparative ease. The prin- 

 cipal insect vectors of important human 

 diseases have been brought under control 

 to such a degree that the once dreaded 

 diseases — malaria, typhoid fever, dysen- 

 tery, cholera, and bubonic plague- — are 

 little more than an unhappy memory. 

 Reasonably effective measures for the con- 

 trol of important household pests such as 

 the bedbug, cockroaches, stored-grain 

 pests, clothes moths, and carpet beetles 

 have brought peace of mind to the house- 

 wife and have contributed much to in- 

 crease the comfort of the home. Measures 

 developed for the control of insects at- 

 tacking livestock — ticks, tabanids, stable 

 flies, lice, and screwworms — have contrib- 

 uted much to the livestock industry. The 

 successes mentioned above were attained 

 despite the drastic rise in level of accep- 

 tance imposed by the public, the United 

 States Food and Drug Administration, 

 and market grades and standards. Under 

 present regulations, the diseased and dam- 

 aged condition of fruits, vegetables, grain, 

 and other agricultural products that were 

 accepted at the turn of the century would 

 eliminate them from moving in interstate 



