No. 7. 



Observations on the Hessian Fly. 



229 



For the Fanners' Cabinet. 

 Observations on the Hessian Fly. 



The investiiration of the character and 

 habits of the Hessian Fly having occupied 

 some portion of my time, I was much pleased 

 with the able and learned paper by Dr. 

 Coates, on this insect, published in the last 

 number of the Farmers' Cabinet. 



The subject is one of the greatest impor- 

 tance, not only to the farmer individually, as 

 affecting one of his principal products, but to 

 the nation at large, by involving all the con- 

 sequences attendant on a deficiency or abun- 

 dance of a principal and essential article of 

 commerce. 



To acquire a perfect knowledge of this 

 insect, and its habitudes with the growing 

 wheat, will, I am fully persuaded, demand 

 the closest and most scrutinizing attention. 

 It was therefore with pleasure that I observed 

 Miss Morris was labouring in this wide field 

 of remark. Females are, by nature, endowed 

 with more delicate nerves, and more acute 

 perception, than commonly belong to our sex ; 

 entomology, therefore, is a very appropriate 

 study for them. It is to be hoped that Miss 

 Morris will pursue her inquiries, and that she 

 may be able, ultimately, to give a true de- 

 velopment of this obscure subject. 



From my limited observation on this de- 

 structive little insect, I am far from being 

 satisfied with its history and habits ; and I 

 write more with a view of obtaining know- 

 ledge, than from a hope of being able to im- 

 part much that shall be new or useful. But 

 let us first inquire, What is the Hessian fly ] 

 Until this question is satisfactorily answered, 

 all further investigation would be fruitless. 

 To ascertain this fact I took, on the 20th of 

 June 1836, fifty stalks of growing wheat, 

 which were known to contain pupa of some 

 insect. These I placed in a large glass jar, 

 containing, at the bottom, a sponge saturated 

 with water, to supply moisture ; the top 

 was secured by a tin cover, nicely fitted, in 

 which were several small perforations, to 

 admit air, as well as to allow the exhalations 

 to escape. This received my daily notice. 

 About the middle of July, two weeks after 

 the wheat had been cut in the field, I ob- 

 served the first insect in the jar, and, in a few 

 days thereafter, many others. They were 

 restless, little black-winged insects, about 

 one-tenth of an inch in length, much resem- 

 biinof winged ants, except that they were not 

 furnished with those horny jaws, with which 

 the latter will always bite, when pressed. 

 They were, in short, Hessian flies, such as are 

 described by entomologists. As the descrip- 

 tion from Say, given by Dr. Coates, page 204, 

 Vol. 5, of the Cabinet, entirely corresponds 

 with the insects I had in my jar, it is not i 



necessary to repeat it here. During all the 

 time of making this experiment I daily visited 

 my wheat-field, and found that the change 

 going on there, from the pupa state to the 

 perfect insect, was cotemporaneous with that 

 in the jar. The insect escapes from confine- 

 ment, under the sheath of the leaf, by eating 

 a hole through it, its strength being insuffi- 

 cient to burst it asunder. Such, then, is the 

 Hessian fly, or wheat-insect ; but there are 

 many other interesting particulars to learn 

 respecting it. When does it deposit its eggs ■? 

 Where? What remedy can be proposed to 

 counteract its operations on the growing 

 crops of wheat? All these questions are 

 more easily asked than answered. 



In a paper to which I gave publicity in 

 August 1836, the opinion was expressed that 

 the eggs were always deposited in the fall ; 

 that the insect was too feeble to withstand 

 the severity of winter, and could not, of 

 course, deposit them in the spring. Subse- 

 quent observation has convinced me that I 

 was in error. In potatoe and turnip patches, 

 the crops of which are frequently gathered so 

 late that wheat sown on them does not get 

 above ground before spring, yet the crops of 

 wheat, thus circumstanced, are frequently 

 entirely destroyed by flies. The same obser- 

 vation may sometimes be applied to whole 

 fields sowed very late. The eggs, then, are 

 deposited both spring and Jail. 



Next, as to the place. The eggs, the 

 larvte, and the pupse, are all, successively, 

 found under the sheath of the leaf, near a 

 joint of the stalk — more commonly the lower 

 joint, in contact with the stalk. The plain 

 inference then is, that the insect pierces the 

 sheath of the leaf with its oviduct, and de- 

 posits the eggs between it and the stalk, in 

 the very position in which they are found ; 

 for it is evident, that in at least two stages 

 of its existence, the insect has not the power 

 of locomotion. Yet, as I am frank to acknow- 

 ledge that I have never detected the insect 

 in the act of depositing its eggs, the theory 

 of Miss Morris may be the correct one ; but 

 I rather incline to the opinion that the insect 

 on which she has made her observations is 

 of the genus curculio. It is well known that 

 an insect of this kind, commonly called the 

 weevil, sometimes deposits its egg in the 

 grain, but it remains there until it comes out 

 a perfect insect. The same is the case 

 with the curculiones, which deposit their 

 eggs in peas, and smooth-skinned stone-fruits, 

 such as nectarines, plums, &c. But having 

 got once safely esconced, they seem, by in- 

 stinct, satisfied to remain and undergo the 

 metamorphosis in the position in which they 

 have, by the parent, been placed. 



We have now arrived at the most difficult 

 part of our subject — the remedy. From the 



