FLY, HESSIAN. 



her upon the blade, and wrapped her up in a 

 piece of paper. I then proceeded to take up 

 the plant with as much as I conveniently could 

 of the circumjacent earth, and wrapped it all 

 securely in a piece of paper. Alter that I 

 continued my observations on the flies, caught 

 several similarly occupied, and could see the 

 eggs uniformly placed in the longitudinal cavi- 

 ties of the blades of the wheat ; their appear- 

 ance being that of minute reddish specks. My 

 own mind being thus completely and fully 

 satisfied as to the mode in which the egg was 

 deposited, I proceeded directly to my dwelling, 

 and pit the plant with the egijs upon it in a 

 large glass tumbler, adding a little water to the 

 earth, and secured the vessel by covering it 

 with paper, so that no insect could get access 

 to the interior. The paper was sufficiently 

 perforated with pin-holes for the adini- 

 air. The tumbler with us contents was daily 

 watched by myself to discover the hatching of 

 \bout the middle of the fifteenth 

 MI of the eggs, I was so for- 

 tunate a^ t.) discover a very small maggot or 

 worm, of a reddish cast, making its v. 

 considerable activity down the blade, and saw 

 it till it disappeared between the blade and 

 stem of the plant. This I have no doubt, was 

 the produce of one of the eggs, and would, I 

 presume, have hatched much sooner, had the 

 plant remained in the field. It was my inten- 

 tion to have carried on the experiment, by en- 

 deavouring to hatch out the insect from the 

 flax-seed Mate into the perfect ny again ; but 

 being called from home, the plant was suffered 

 to pensh. The fly that I caught on the blade of 

 the wheat, as above stated, I enclosed in a letter 

 to Mr. John 8. Skinner, the editor of the jJmtri 

 can Fdi-tmr, of Baltimore, who pronounced it 

 to be a genuine Hessian fly, and identical in 

 appearance with others recently received from 

 Virginia. 1 



44 Dr. Chapman agrees with the writer, in 

 saving that the Hessian fly lays her eggs in 

 the small creases of the young leave^ 

 wheat. Mr. Havens, in an article on this in- 

 sect, which will again be referred to, states, 

 that the ily lays her eggs on the leaves. In the 

 fortieth number of The Connecticut Fanner't 

 . Mr. Herrick says, ' I have repeatedly, 

 both in autumn and spring, seen the Hessian 

 fly in the act of depositing eggs on wheat, and 

 have always found that she selects for this pur- 

 pose the leaves of the young plant. The eggs 

 are laid in various numbers on the upper sur- 

 face of the strap-shaped portion (or blade) of 

 the leaf.' His remarks in Professor Siiliman's 

 Journal are to the same effect. Other authori- 

 ties on this point might be mentioned; but the 

 foregoing are sufficient, in my opinion, to 

 establish the fact, that the Hessian fly lays her 

 eggs on the leaves of wheat soon after the 

 plants are up. ' The number on a single leaf,' 

 says Mr. Herrick, ' is often twenty or thirty, 

 and sometimes much greater. In these cases 

 many of the larvae must perish. The egg is 

 about a fiftieth of an inch long, and four-thou- 

 sandth of an inch in diameter, cylindrical, 

 translucent, and of a pale red colour.' Mr. I 

 Tilghman v as correct in supposing that the 

 eggs would hatch in less than fifteen days, i 



FLY, HESSIAN. 







under favourable circumstances ; for, if the 

 weather be warm, they commonly hatch in four 

 days after they are laid. The maggots, when 

 they first come out of the shells, are of a pale 

 red colour. Forthwith they crawl down the 

 leaf, and work their way between it and the 

 main stalk, passing downwards till they come 

 to a joint, just above which they remain, a 

 i little below the surface of the ground, with the 

 head towards the root of the plant. Having 

 thus fixed themselves upon the stalk, they be- 

 come stationary, and never move from the 

 place till their tran.sfonnations are completed. 

 They do not eat the stalk, neither do they pene- 

 trate within it, as some persons have supposed, 

 but they lie lengthwise upon its surface, 

 covered by the lower part of the leaves, and 

 are nourished wholly by the sap, which they 

 appear to take by suction. They soon lose 

 their reddish colour, turn pale, and will be 

 found to be clouded with whitish spots; and 

 through their transparent skins a greenish 

 stripe may be seen in the middle of their 

 bodies. As they increase in size, and grow 

 plump and firm," they be.come imbedded in the 

 side of the stem, by the pressure of their bodies 

 upon the growing plant. One maggot thus 

 placed seldom 'i plant; but when two 



or three are fixed in this manner around the 

 -t'-m, they weaken and impoverish the plant, 

 and cause it to fall down, or to wither and die. 

 usually come to their full size in five or 

 six weeks, and then MKMMIIV about three-twen- 

 tieths of an inch in len-ih. Their skin now 

 gradually hardens, becomes brown i>h, and 

 changes to a bright chestnut colour. This 

 change usually happens about the first of De- 

 cember, when the m>'-ct may be said to enter 

 on the pupa state, for after this time it takes no 

 more nourishment. Mr. Herrick informs me, 

 that the brown and leathery skin, within which 

 the maggot has changed to a pupa or chrysalis, 

 is long, egg-shaped, smooth, and marked with 

 eleven transverse lines, and measures one- 

 eighth of "an inch in length. In this form it 

 has been commonly likened to a flax-sted. It 

 appears, then, from the remarks of Dr. Chap- 

 man, Mr. Herrick, and other careful observers, 

 that the maggots of the Hessian fly do not cast 

 off their skins in order to become pupce, v/here- 

 in they differ from the larvae of most other 

 gnats, and agree with those of common flies ; 

 neither do they spin cocoons, as some of the 

 Cecidomyians are supposed to do. Mr. Her- 

 rick, in one of his letters, observes, that ' the 

 pupa gradually cleaves from the dried skin of 

 the larva, and, in the course of two or three 

 weeks, is wholly detached' from it. Still en- 

 closed within this skin, which thus becomes 

 a kind of cocoon or shell for the pupa, it 

 remains throughout the winter, safely lodged 

 in its bed on the side of the stem, near the 

 root of the plant, and protected from the cold 

 by the dead leaves. Towards the end of April 

 and in the forepart of May, or as soon as the 

 weather becomes warm enough in the spring, 

 the insects are transformed into flies. They 

 make their escape from their winter-quarters 

 by breaking through one end of their shells 

 and the remains of the leaves around them. * 

 " Very soon after the flies come forth in the 



195 



