HABITS OF THE HESSIAN FLY. 579 



their eggs for the space of three weeks, after which they 

 entirely disappear from the fields. The maggots, hatched 

 from these eggs, pass along the stems of the wheat, nearly 

 to the roots, become stationary, and take the flax-seed 

 form in June and July. In this state they are found at 

 the time of harvest; and, when the grain is gathered, 

 they remain in the stubble in the fields. To this, how- 

 ever, as Mr. Havens remarks, there are some exceptions ; 

 for a few of the insects do not pass so far down the side 

 of the stems as to be out of the way of the sickle when 

 the grain is reaped, and consequently will be gathered and 

 carried away with the straw. Most of them are trans- 

 formed to flies in the autumn, but others remain unchanged 

 in the stubble or straw till the next spring. Hereby, says 

 Mr. Havens, " it appears evident that they may be re- 

 moved from their natural situation in the field, and be 

 kept alive long enough to be carried across the Atlantic ; 

 from which circumstance it is possible that they might have 

 been imported" in straw from a foreign country. 



In the winged state, these flies, or more properly gnats, 

 are very active, and, though very small and seemingly 

 feeble, are able to fly to a considerable distance in search 

 of fields of young grain. Their principal migrations take 

 place in August and September in the Middle States, 

 where they undergo their final transformations earlier than 

 in New England. There, too, they sometimes take wing 

 in immense swarms, and, being probably aided by the wind, 

 are not stopped in their course either by mountains or riv- 

 ers. On their first appearance in Pennsylvania, they were 

 seen to pass the Delaware like a cloud. Being attracted 

 by light, they have been known, during the wheat harvest, 

 to enter houses in the evening in such numbers as seri- 

 ously to annoy the inhabitants.* 



Mr. Havens has alluded to " an opinion, entertained by 



* British, and Dobson's Encyclopaedia, and Colonel Morgan's letter in Carey's 

 American Museum, Vol. II. p. 298. 



