The Hessian Fly. 307 



THE HESSIAN FLY. 



'"The following account oftlie Hessian Fly, (Cecidomt/la destruc" 

 tor,) see plate, is condensed from Dr. Harris' Treatise on the Insects 

 of New England, injurious to Vegetation. This insect was first 

 observed in the year 1776, in the neighbourhood of Sir William 

 Howe's debarkation on Staten Island, and at Flatbush on the west 

 end of Long Island, New York, It is properly a small, two- 

 winged gnat, which lays its eggs in winter or fall in wheat, when 

 the grain has sprouted and begins to show leaves. 



*' According to the account of Mr. Edward Tilghman, of Queen 

 Ann County, Maryland, the eggs are deposited in October, in the 

 longitudinal cavities between the little ridges of the blade, from 

 which, in about fifteen days, very small worms or maggots appear. 

 They make way down the blades with considerable activity until 

 hidden between them and the stems of the plants. Mr. Herrick, 

 in the " Connecticut Farmer," says : " I have repeatedly, both in 

 autumn and spring, seen the Hessian Fly in the act of depositing 

 eggs on wheat. The number on a single leaf is often twenty or 

 thirty, and sometimes much greater." The eggs are extremely 

 minute, and of a pale red color ; and if the weather prove favora- 

 ble they will hatch in four days. The maggots, when they first 

 come out of their shells, are also of a pale red color. Forthwith 

 they crawl down the leaves and work their way between them and 

 the main stalk, passing downwards till they come to a joint, just 

 above which they remain, a little below the surface of the ground, 

 with the head towards the root of the plant. Having thus fixed 

 themselves upon the stalk, they become stationary, and never 

 move from the place before their transformations are completed. 

 They do not eat the stalk, neither do they penetrate withan it, 

 as some persons have supposed, but lie lengthwise on its surface 

 covered by the lower part of the leaves, and are wholly nourished 

 by the sap, which they appear to take by suction. They soon lose 

 their reddish color, 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 become imbedded in 

 the side of the stem by the pressure of their bodies upon the grow- 

 ing plant. One maggot thus placed seldom destroys the plant ; 

 but when two or three are fixed in this manner around the stem 

 they weaken and impoverish it, and cause it to fall down, or wither 

 and die. They usually come to their full size in five or six weeks 

 and then measure about three-twentieths of an inch in length. 

 Their skins now gradually harden, become brownish, and soon 

 change to a bright chestnut color, which change usually happens 

 about the first of December. The insect, in this form, has been 

 commonly likened to flax-seed ; hence many observers speak of 

 this as the " flax-seed state." In two or three weeks after this 

 change of color, the insect within becomes entirely detached from 

 tke old larva skin, and lies within it a motionless grub. The 



