68 



As may be inferred from sOffle parts of the Dociafs letter lasf 

 quoted, I had suggested an inquiry as to what had been raised on 

 the lands the previous year, and also whether a rotation of crops 

 would not prove at least a partial remedy against the ravages of 

 this insect, but this may be appropriately discussed under the head 

 of remedies. Up to this point in our investigations we had found 

 out but little of the habits of the insect, aside from the fact that 

 the larvae ate the roots of corn, and that the beetles were to be 

 found in the corn and upon the flowers of ragweed and other weeds. 

 From the last it might be inferred that ordinarily the weeds consti- 

 tuted then- food, both in the larva as well as in the perfect state. 

 Acting upon this hint, Dr. Boardman made farther examinations 

 both in the cornfields and among the weeds, when he wrote me 

 again, first under date of August 30th: 



"The larvae appear to be all out of the corn roots, and the beetles 

 laave gone into tlie ends of the ears in large numbers, but I cannot 

 find that they are depositing any eggs there. They seem to be 

 feeding on the kernel. A storm on the 27th prostrated whole fields 

 that had been undermined by them. Corn on stubble land is stand- 

 ing and looks fair." 



Under date of August 31st he writes again: 



^'l have found to-day larvae of D. Longicornis in com roots and 

 in I'oots of i'agweed, proving conclusively that they are more than 

 one-brooded. Where the beetle enters the ear it eats the silk (pistil) 

 off, and in many instances, I think, has injured the e&m by doing 

 it before the ovum has become fecundated, and by so doing pre- 

 vented the corn from filling." 



This gave us some valuable data m regard to the food of the in- 

 sect in its different stages. Dr. B., in his communicatioe of August 

 5th, says he usually found them abundant on thistles, and that 

 during that season — 1880 — they were more troublesome to his vines 

 than D. Vittata, the usual cucumber and squash beetle. We might 

 suppose that they frequented thistles and other flowers, but we are 

 not left to conjecture on this point. Among other possible remedies, 

 I had, in one of my articles in the Prairie Farmer, suggested that 

 the birds might aid in reducing the number of these beetles. In 

 response to this. Prof. S. A. Forbes, of Normal, 111., who has been 

 making the food of birds and other animals a special study, writes 

 me under date of August 28th, 1880, as follows: 



"Diahrotica Longicornis is one of our most abundant beetles here 

 in August and September, on thistles — occasionally, also, on Golden, 

 rods and some other compositae. I have never noticed it on Am- 

 brosia, however. Mr. Peters brought in a number this afternoon, 

 and I opened the stomachs of two of them and found the whole 

 alimentary canal packed with thistle pollen. I have never found 

 the species in any bird." 



In regard to the food of this beetle, I might add that I have this 



year 1881 — found them in considerable numbers in my black wax 



beans, in my garden. Upon this point, as well as the prevalence 

 of the insect this season, Mr. F. M. Webster, of Waterman, De- 

 Kalb county, writes under date of September 21st, 1881 : 



"While upon the subject of green, I wish to say that those little 

 miserable green Diahrotica Longicornis are swarming all over our 



