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 bv 
* British, and Dobson’s Encyclopaedia, and Colonel Morgan’s letter in Carey’s 
American Museum, Yol. II. p. 296. 
