9 FARMERS’ BULLETIN 636. 
In the fall of 1912 an investigation was started with a view to 
determining some practical method of checking this pest. Much 
of this work is still in an experimental stage, but certain practices 
are at hand whereby the grower of alfalfa seed may reduce the num- 
bers of this insect in his fields and without doubt profit largely by 
the results. 
The different sections in which investigations have been conducted 
present in themselves many local problems which must necessarily 
be omitted in this brief preliminary account of an insect which is so 
widely distributed and so destructive. Nevertheless this bulletin 
will serve to give the alfalfa-seed grower a general knowledge of the 
chalcis-fly, together with such information as will direct him in adopt- 
ing measures for reducing the large annual loss due to its work. 
DEVELOPMENT AND HABITS. 
The eggs are very small; in fact, they are invisible to the naked 
eye, and are deposited through the soft green seed pods directly into 
the soft seeds. Under field conditions oviposition usually takes 
place when the pods are about half grown. The time required for 
the eggs to hatch varies greatly. Under favorable temperatures the 
larvee (fig. 1, 6) begin feeding in about a week after the eggs have 
been deposited. The larve feed within the soft, tender, growing 
seeds, and before the pods have had time to ripen most of them have 
become full grown. 
When there is sufficient moisture remaining in the seed pods, most 
of the larve at once transform to the pupal stage, but if the seeds 
become thoroughly dry before the larvee enter the pupal stage (fig. 
1, c) this transformation may be delayed indefinitely and the larve 
remain dormant until the following spring or some other time when 
both moisture and temperature are favorable for their transforma- 
tion. In the pupal stage the insect may rest from 10 to 40 days 
before emerging as an adult. 
All of the stages of development are completed within the infested 
seeds. 
Immediately upon becoming adult (fig. 1, a). the chalcis-flies eat 
their way out through the remaining shells of the infested seeds, 
then through the seed pods (fig. 3), leaving in each case a hollow 
seed (fig. 2). The adults may be seen in great numbers flying over 
alfalfa-seed shocks and swarming over the sickle bar when the crop 
is being cut. They are frequently confused with gnats. 
The chalcis-flies are most active in hot weather, but seek the shade 
in the heat of the day. They visit the alfalfa blossoms apparently 
to secure food, and in moderate weather live to be several weeks old. 
