December, 1958 



Deckkr: Economic Entomology 



117 



killed," is in reality killed by the Hessian fly; 

 and there may be, and probably are, many 

 other insects which depredate upon this crop, 

 but whose habits have not yet fallen under the 

 notice of entomologists (Walsh 1861:335). 



Taking the average of years, we may safely 

 assume that a fifth part of the wheat crop — 

 or, which is the same thing, a quantity equal 

 to one-fourth of what we actually do harvest 

 — is destroyed by insects. Even at the low price, 

 therefore, of 75 cents per bushel, we have 

 over four and a half million dollars' v:orth 

 of wheat annuallv destroyed by "little vermin 

 which it is not worth our while to notice." 

 But this is not all. Other crops are damaged 

 by other insects, though not generally to so 

 ruinous an extent; so that we cannot put the 

 whole annual damage done by insects to the 

 State of Illinois at less than twenty million- 

 dollars (Walsh 1861:336). 



And Thomas (1865:457) wrote: "So 

 much has already been written in the pa- 

 pers of this State concerning the Chinch- 

 bug {\lacropus leucopterus. Fitch,) that 

 I shall pass it by in this paper without 

 further notice." 



Shelford (Sc Flint (1943) made a thor- 

 ough study of the history of the chinch 

 bug in Illinois. The figure on page 116 

 is presented to illustrate the type of his- 

 toric records that have been made and 

 preserved by the Natural History Sur- 

 vey. The data on which the figure is 

 based cover the century beginning in 

 1840. Records for subsequent years have, 

 of course, been kept. Similar data have 

 been collected for several other important 

 pests. 



In the 1860"s and 70's, many measures 

 were proposed for control of the chinch 

 bug: abandon wheat and barley or corn; 

 burn fencerows and all wild grass areas 

 to destroy hibernating bugs ; plant border 

 crops to retard migrations ; fertilize crops 

 to get dense stands unattractive to the in- 

 sects; and construct barrier lines of lime, 

 salt, and carbolic acid solutions. The 

 measure most widely used was the dusty 

 furrow. Each year saw some new version 

 of the furrow proposed, such as pouring 

 tar oil, road oil, or creosote into the fur- 

 row to form a barrier; covering the fur- 

 row with straw and setting it afire to de- 

 stroy the bugs ; digging post-hole traps in 

 the furrow and later spraying the trapped 

 bugs with kerosene and burning them. 

 There was no great change until the 

 paper fence barrier, proposed in 1934, 

 was widely adopted, but even this barrier 



was not without precedent; over 50 years 

 earlier the use of tar-covered boards set 

 on edge and placed end to end had been 

 proposed. The later control measures, 

 like the early ones, were scheduled to be 

 used around harvest time. About 1945, 

 the paper fence barrier was practically re- 

 placed by the dinitro dust barrier, and in 

 another 10 years this was replaced by diel- 

 drin, spraj'ed on strips of ground along 

 the margins of small grain fields where 

 these fields adjoined fields of corn or later 

 maturing grain. The more aggressive fol- 

 lowers of research progress were spray- 

 ing entire fields of heavily infested wheat 

 as soon as chinch bug eggs began to hatch 

 so as to protect the wheat crop itself 

 from serious damage and to eliminate the 

 necessity of establishing a barrier of any 

 type 2 or 3 weeks later. 



In the past century, progress has been 

 made in controlling many other insect 

 pests that attack cereal and forage crops. 

 Among the most important of these pests 

 are the grasshoppers, the cutworms, the 

 white grubs, and the hessian fly. Instead 

 of attempting to summarize in detail, we 

 note here some of the general trends in 

 this area of insect control. 



Before extensive agricultural develop- 

 ment of the state, a large part of Illinois 

 consisted of broad expanses of prairie 

 grass, much of which was replaced by 

 timothy and other tame grass or cereal 

 crops planted by farmers. Insects prefer- 

 ring these crops became notorious pests, 

 but as the acreage of grasses was reduced 

 as a result of increased legume produc- 

 tion, certain insects began to decline in 

 importance. These included the white 

 grubs, the billbugs, the armyworms, the 

 sod webworms, and the corn root aphid. 

 The burrowing webworm and the cut- 

 worm Liiperina stipata have all but dis- 

 appeared ; not a single specimen of either 

 has been received by us for identification 

 in the last 20 years. As the rail fence was 

 replaced by the wire fence, and roadsides 

 and ditch banks were graded or otherwise 

 cleaned up, the amount of giant ragweed 

 and elderberry available to insects was 

 greatly reduced, so that the common stalk 

 borer became less important and the old 

 spindleworm was practically extermin- 

 ated. Likewise, as the pot holes and low 

 spots were drained, wireworm damage in 



