462 INSECTS INJURIOUS TO VEGETATION. 



Very soon after the flies come forth in the spring, they are 

 prepared to lay their eggs on the leaves of the wheat sown in 

 the autumn before, and also on the spring-sown wheat, that 

 begins, at this time, to appear above the surface of the ground. 

 They continue to come forth and lay 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, 

 however, 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 transformed 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 removed 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 rivers. On their first ap- 

 pearance 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 seriously to annoy the inhabitants.* 



* British and Dobson's •' Encyclopsedia," and Colonel Morgan's letter in 

 Carey's "American Museum," Vol. II., p. 298. 



