26 Insects hjurious to Vegetation. £Jan., 



result of burning the stubble of the wheat field. We commenced 

 our account of this remedy impressed with a belief that it was 

 the best that had ever been proposed; we close it, persuaded that 

 it is the very worst. 



Brief Summary of the preceding History. 



The Hessian fly [Cecidomyia destructor of Say,) is a Euro- 

 pean insect, and has been detected in Germany, France, Switzer- 

 land and Italy, where it at times commits severe depredations 

 upon the wheat crops. Its ravages are alluded to so far back as the 

 year 1732. It was brought to this country, probably in some 

 straw used in package by the Hessian soldiers, who landed on 

 Staten and the west end of Long Island, August 1776, but did 

 not become so multiplied as to severely injure the crops in that 

 neighborhood, until 1779. From thence as a central point, it 

 gradually extended over the country in all directions, advancing 

 at the rate of from ten to twenty miles a year. Most of the wheat 

 crops were wholly destroyed by it within a year or two of its first 

 arrival at the given place, and its depredations commonly con- 

 tinued for several years, when they would nearly or quite cease; 

 its parasitic insect enemies probable increasing to such an extent 

 as to almost exterminate it. It is frequently reappearing in ex- 

 cessive numbers in one and another district of our country, and in 

 addition to wheat, injures also barley and rye. 



There are two generations of this insect annually. The eggs 

 resemble minute reddish grains, and are laid in the creases of the 

 upper surface of the leaf, when the wheat is but a few inches high, 

 mostly in the month of September. These hatch in about a week, 

 and the worm crawls dovv-n the sheaf of the leaf to its base, just 

 below the surface of the ground, where it remains, subsisting upon 

 the juices of the plant, without wounding it, but causing it to turn 

 yellow and die. It is a small white maggot, and attains its growth 

 in about six weeks. It then changes to a flax seed like body, 

 within which the worm becomes a pupa the following spring, and 

 from this the fly is evolved in ten or twelve days. The fly closely 

 resembles a musquitoe in its appearance, but isa third smaller, and 

 has no bill for sucking blood; it is black, the joints of its body 

 being slightly marked with reddish. It appears early in May, 

 lays its eggs for another generation and soon perishes. The worms 

 from these eggs nestle at the lower joints of the stalks, weakening 

 them and causing them to bend and fall down from the weight of 

 the head, so that towards harvest, an infested field looks as though 

 cattle had passed through it. 



Wheat can scarcely be grown except upon a fertile soil in those 

 districts where this insect is abundant The sowing should be 



