FARMEES' INSTITUTES. 69 



name was first given by Col. George Morgan, because he supposed it to have 

 been brought from Europe as pupa?, concealed in the straw, which was shipped 

 upon the vessel bearing the Hessians to this country. The liabits of the fly, 

 as will be shown, readily admit of such transportation. Commencing then at 

 New York, westward the scourge of empires takes its way, progressing from 

 twenty to thirty miles each year until in 1860 we find them settled in Iowa 

 and Minnesota. 



One of the seemingly curious facts in connection with the Hessian fly, is its 

 sudden appearance for short periods and then its apparent disappearance. 

 Thus in 1872, it was among us in Michigan, and also south and southwest. It 

 was not noticed again until it celebrated its centennial in the southern part of 

 this State, appearing as far north as the capital. Tliis going and coming is 

 easily accounted for (though to the close observer it is well known that there 

 are always some few to be found), and is particularly noticeable in all insects 

 which are not provided with some odor or other means of defense against para- 

 sites and birds. Insects having such means of defense are very uniform in 

 number. Is it not then safe to reason that we are indebted to the parasitic 

 enemies of the Hessian fly for its short absence? As these enemies become 

 more numerous, more larva? of the fly must perish from their attacks which 

 are made by laying an egg in each egg of the fly. These parasitic enemies 

 are somewhat inclined to become gluttons, and in a few seasons not enough 

 flies will remain to furnish them with sufficient eggs for their deposits, and 

 consequently some of tlie parasite's eggs must suffer death. Another season 

 still more must perish, until finally the flies become nearly extinct. In the 

 meanwhile there will always be some few of the Hessian flies left. After the 

 parasites are gone these flies will increase until they become legion, showing 

 their presence by laying waste our wheat fields ; this work will continue until 

 the nucleus of the parasites shall have grown into supremacy, when another 

 disappearance of the fly will be noticed. 



This insect is very small and might pass for a mosquito to the casual ob- 

 server. The imago fly is black with the wing bases, joints, underside of body 

 and legs of a tawny or light yellow color. Just previous to laying her eggs 

 the well stocked abdomen of the female is rose colored, like that of a well 

 filled mosquito; this color is given by some two hundred eggs which are of a 

 redish color, alighting upon the surface of a leaf she places from one to ten 

 eggs in its creases, in from twenty seconds to a minute of time, and is off im- 

 mediately in quest of more mischief. In from four to fifteen days, depending 

 upon the weather, these eggs hatch into minute maggots which at once com- 

 mence a journey down the leaf ; working tiiemselves in between it and the 

 main stalk, they continue toward the root until they come to a joint just below 

 the ground surface ; they here fix themselves upon the stalk and remain station- 

 ary until completing their transformations. While in this position they do not 

 eat the stalk, for maggots have no jaws, neither do they enter the inside of the 

 stalk, but lying lengthwise upon its surface, they are nourished by the sap 

 which they take in by absorption. It is the loss of this sap that causes the 

 wheat plant to perish. After remaining thus for five or six weeks the mag- 

 got takes on a rich mahogany color, becomes hard, and is said to be in the 

 flaxseed state. 



In passing through an infected field we will see many yellow, drooping plants; 

 pulling one of these and stripping down the outside leaf of the now worthless 

 plant, we shall find tlie cause of all this in the little hollow which his body 

 has formed in the stalk. There are two broods each wheat year, and favorable 



