50 
Tho the full-grown larvae may simply drop to the ground, as other 
writers have stated, they frequently wriggle their way down along the 
stem of the plant, when the latter is wet with rain. Indeed, the larvre, 
even when full grown, will not emerge if the air is too dry. Ceci- 
domyiid larvae in general require considerable moisture for their de- 
velopment and are very sensitive to the influence of humidity. Dry- 
ness causes the seed-midge larvae, when on the ground, to squeeze 
themselves into crevices in the soil and to contract the body and become 
motionless, as if for pupation. Even then, however, moisture will re- 
peatedly revive them to a condition of wriggling activity. 
The period of pupation is lengthened by dryness and shortened by 
moisture. Prolonged dryness kills both larvae and pupae. Out-of-doors 
the flies do not emerge during a dry spell ; continuous dry weather 
will delay their appearance as much as two weeks ; but they may be 
expected to appear after a rain, in the appropriate part of the season. 
In the insectary, the emergence of the flies can be similarly controlled 
by moisture, as G. C. Davis has already noted. 
Riley states that the pupa works itself thru its cocoon and to the 
surface of the ground when about to give forth the fly. 
Autumn finds larvae of various sizes in the clover heads, in central 
Illinois. Most of the larvae become full grown and go to the ground 
in September ; the rest remain in the heads and either finish their growth 
or else succumb to frost. In spite of frosts, full-sized larvae may be 
found in the heads as late as the middle of October. October 28, 1907, 
we found in clover heads several larvae which were so small (0.8 mm. 
in length) that they must have been derived from late September flies, 
and they were altogether too small to survive the imminent death of 
their food plant. 
The recognized injury done by the seed-midge to red clover occurs 
during the second year of the plant, and the amount of injury increases 
the longer the plant is allowed to run. 
Vigorous plants, however, form heads during their first year, and 
in these premature heads not a few larvae of the seed-midge are to be 
found in autumn. 
Natural Enemies. — The chalcid, Bruchophagus (Eurytoma) fune- 
bris How., at first suspected of being parasitic upon the larva of the 
seed-midge, is now known to destroy the seed instead of the larva, 
taking what the seed-midge leaves. 
We have reared from clover heads containing larvae of the seed- 
midge two as yet undetermined species of the chalcid genus Tetrasti- 
chiis. These are possibly the same two that are mentioned by Webster 
as having been reared directly from both larvae and pupae obtained 
about Lincoln, Neb., in December. In Delaware, Sanderson bred from 
larvae of the seed-midge, in October, 1899, and in June, 1900, parasites 
determined by Ashmead as Tetrastichus carinatus Forbes and Torymns. 
Another parasite of the seed-midge is Anopedias error Fitch, of 
the family Platygasteridce, a minute black species, about which almost 
nothing has been written since Comstock, in 1880, reported it as emerg- 
ing from the cocoon of the clover seed-midge. 
