The Hessian Fly, and its Parasites. 160 



the 4th of June, 1834, he obtained similar pupae from a wheat 

 field near Naples. — About the period of Mr. Dana's investigations 

 in the south of Europe, attention was turned to the injury 

 caused by certain larvae among the wheat in Hungary. It ap- 

 pears now to be commonly believed, that their parent insect is 

 either our Hessian fly, or an animal very closely allied to it. 



I have searched in vain for any traces of the Hessian fly in 

 this country before the Revolution. The Rev. Jared Eliot, in 

 his " Essays upon Field Husbandry in New England,'''' Boston, 

 1760, treats of the culture of wheat, but makes no allusion to 

 any insect having habits like those of the Hessian fly : neither 

 does Kalm, the naturalist, who travelled in this country about 

 1750. I am therefore inclined to consider the common opinion 

 of the origin of the insect quite as probable as any other which 

 has been advanced. 



In this part of our country, wheat is usually sown about the 

 first of September. Soon after the plants are up, the Hessian fly 

 begins to lay her eggs upon them, and continues her operations 

 for several weeks. She deposits her eggs on the upper surface of 

 the leaf (i. e. the ligula, or strap-shaped portion of the leaf) of 

 the plant. The number on a single leaf 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 hundredths of an inch in diameter, cylindrical, translucent, 

 and of a pale red color. In about four days the egg hatches ; the 

 young larva creeps down the leaf, enters the sheath, and with 

 the head downwards, fastens upon the tender culm or stalk, gen- 

 erally just above some joint. The larva appears to feed solely 

 on the sap of the plant ; it does not gnaw the stalk, and never 

 enters it, but is gradually imbedded in it as the plant matures. 

 Having taken its post, the larva is stationary ; it gradually loses its 

 reddish color, becomes translucent, and clouded with white spots, 

 and when near maturity, the central part within is of a greenish 

 hue. In about five or six weeks, (or longer if the season is cold,) 

 the larva begins to assume a brownish tinge, and soon is of a 

 bright chestnut color, when the insect may be said to have reached 

 the state of pupa. It has then some resemblance to a flax-seed. 

 The outer skin of the larva becomes the puparium of the pupa. 

 The wheat plant is injured by the loss of sap, but principally by 

 the pressure of the larvae and pupae upon the culm. A single 



