DIPTERA. 429 



gnats, are very active, and, though very small and seemingly 

 feeble, are able to My 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 appearance in Penn- 

 sylvania 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 se- 

 riously to annoy the inhabitants.* 



The old discussion, concerning the place where the Hessian 

 fly lays her eggs, has lately been revived, in consequence of a 

 communication made by Miss Margaretta H. Morris, of Ger- 

 mantown, Pennsylvania, to " the American Philosophical So- 

 ciety," of Philadelphia. The following remarks upon it are 

 extracted from a Report made to the same Society, and pub- 

 lished in their ''Proceedings" for November and December, 

 1840. " Miss Morris believes she has established that the 

 ovum (egg) of this destructive insect is deposited in the seed of 

 the wheat, and not in the stalk or culm. She has watched the 

 progress of the animal since June, 1836, and has satisfied her- 

 self that she has frequently seen the larva within the seed. She 

 has also detected the larva, at various stages of its progress, from 

 the seed to between the body of the stalk and the sheath of the 

 leaves. According to her observations, the recently hatched 

 larva penetrates to the centre of the straw, where it may be found 

 of a pale greenish white semitransparent appearance, in form 

 somewhat resembling a silk worm. From one to six of these 

 have been found at various heights from the seed to the third 

 joint." Miss Morris's communication has not yet been published 

 in full ; but, from the foregoing report, we are led to infer, that 

 the egg, being sowed with the grain, is hatched in the ground, 

 and that the maggot afterwards mounts from the seed through the 



* British and Dobson's " Encyclopedia," and Colonel Morgan's letter in Ca- 

 rey's '• American Museum," Vol. II., p. 2U8. 



