December, 1958 



Decker: Economic Entomology 



121 



to mind, in this connection, the computation of 

 Mr. Wilson the ornithologist, the result of 

 which was, that the single species of Red- 

 winged Blackbird, which is usually considered 

 one of the greatest pests of the farmer, con- 

 sumes in one season, in the United States, six- 

 teen thousand and two hundred million of 

 noxious insects (Le Baron 1855:559-60). 



In an essay on insects, prepared in 1861 

 at the invitation of the Illinois A^jricul- 

 tural Society, Cyrus Thomas (1865:462, 

 464) made several pertinent comments 

 on insect control measures, the balance of 

 nature, and the biological control of in- 

 sects : 



When we have obtained a complete knowl- 

 edge of the laws of nature, and shall have at- 

 tained to perfection in agricultural pursuits, 

 then most assuredly our reliance for a check 

 upon these insect enemies will be upon the 

 parasites a kind Providence has provided for 

 our benefit. And the reason for so doing will 

 be that then we will work in accordance with 

 the laws of nature which are adapted to our 

 best method of living and acting. Then if this 

 theory be true, the nearer we can approach 

 such a condition, individually or collectively, 

 the better it will be for us. 



Let the birds go unmolested, or even go so far 

 as to entice them to abide near you. Learn to 

 distinguish insect enemies from insect friends, 

 and when you find the hiding places of the 

 latter, as far as possible, protect them from 

 injury. When you find a swarm of "Lady- 

 bugs" huddling around the root of a tree in 

 the winter, throw a few dry leaves over them 

 that the birds may not see them. When you 

 see the eggs of the Syrphus fly lying singly 

 among those of the Aphis, do not molest it, for 

 the young larvae will surely destroy that nest. 

 And when the bright banded flies hover like 

 bees around vou, during the hot days of sum- 

 mer, while resting beneath the shade, brush 

 them lightly away, and remember they are 

 vour friends. And when you see the eggs of 

 the Lace-winged fly (Hcmcrohiiis) mounted on 

 their long stalks on the leaves of your plants, 

 let them alone, the voracious larvae they pro- 

 duce will soon destroy the most numerous 

 colony of plant lice. 



Benjamin Walsh (1861:339-40, 341) 

 likewise had something to say about the 

 balance of nature and the value of para- 

 sites and predators: 



Now it is universally the case, that when- 

 ever man, by his artificial arrangements, vio- 

 lates great natural laws, unless by some arti- 

 ficial means he can restore the overturned bal- 

 ance, he pays the penalty aflnxed to his ofl^ense. 

 The voluptuary may overload his stomach, but, 

 unless he has recourse to his dinner pill, he 

 pavs the penalty of an indigestion. So with the 

 farmer and the horticulturist. Until they can 



restore the natural e(|uilibrium which has been 

 disarranged by their artificial processes, they 

 pay the penalty in the damage inflicted on 

 them by plant-feeding insects. They must as- 

 sist nature, whenever, for necessary purposes, 

 they have thwarted and controlled her, if they 

 wish to appease her wrath. 



If these views be correct, it would seem to 

 follow, as a necessary consequence, that one 

 of the most effectual means of controlling 

 noxious insects is to be found in the artificial 

 propagation of such cannibal species as are 

 naturally designed to prey on them. 



Although, so far as I am aware, cannibal 

 insects have never yet been bred for utilitarian 

 purposes, yet it is by no means an uncommon 

 practice to collect such as are found at large 

 in the woods and fields, and apply them to sub- 

 due some particular insect that is annoying us. 



The foregoing quotations portray not 

 only the profound interest in biological 

 control that these early entomologists pos- 

 sessed but also the breadth and depth of 

 the general knowledge of the day. 



Forbes, who followed Thomas as State 

 Entomologist, was likewise interested in 

 parasites and predators. The fact is im- 

 pressive that, in studying the biology and 

 ecology of insect pests, these men invaria- 

 bly made extensive notes on the parasites 

 and predators encountered. While others 

 before him had made notes of entomopha- 

 gous fungi and other evidences of disease, 

 Forbes was the first to examine the possi- 

 bilities of control of insects by their dis- 

 eases. In fact, he is regarded by many as 

 the father of insect pathology in the 

 United States. His work on the chinch 

 bug fungus and the work by Dr. F. H. 

 Snow of Kansas are outstanding classics 

 of early research in this field. 



Forbes did not limit his interest and 

 research in insect pathology to chinch bug 

 diseases. He noted, and in many cases 

 studied in great detail, the diseases found 

 in numerous lepidopterous larvae, aphids, 

 white grubs, grasshoppers, and several 

 other insects. In the late 1880's he was 

 strongly advocating more thorough stud- 

 ies on the possible advantageous uses of 

 contagious insect diseases, and his Eighth 

 Report (Nineteenth Illinois Report), 

 published in 1895, contained a monograph 

 of nearly 150 pages on chinch bug dis- 

 eases. In general, the success of attempts 

 to propagate insect diseases and to dis- 

 seminate them as a means of controlling 

 noxious insects in Illinois has not been as 



