4 FARMERS’ BULLETIN 636. 
and growing in the fields. (See fig. 2.) The percentage of aborted 
and worthless seeds is increased by infestation before they are large 
enough to supply the 
growing larve with 
food. In such cases 
both the larve and 
seeds are prematurely 
destroyed. 
When the adults of 
the chalcis-fly emerge 
normally from the al- 
falfa seeds they leave 
nothing but the hol- 
low shell (fig. 2), with 
the opening from 
which the adult has 
escaped near one end. 
A similar opening is 
left in the seed pods, 
directly over that in 
Fic. 3.—Alfalfa seed pods, showing the openings made by the adult the seed (fig. 3) Biome Ice 
chalcis-flies as each escaped from a seed within. (Original.) infested seeds which 
still contain the living larvee of fhe insect may be recognized by their 
®%bnormal shape (fig. 
4), and usually by 
the dull brown color. 
Some of the infested 
seeds, however, retain 
their natural color, 
but they always lack 
the glossy appearance 
of normal seeds. 
EXTENT OF INJURY. 
The extent to which 
alfalfa seed is dam- 
aged by the chalcis- 
fly is not generally ap- 
parent, owing to the 
minuteness of the in- 
sect and because its 
destructive work is Fia. 4.—Infested alfalfa seeds which contained the hibernating larvee 
accomplished — within of the chaleis-fly. (Original) 
the growing seeds. The alfalfa-seed grower can only estimate the per- 
centage of his crop destroyed by opening a large number of the seed 
pods and observing the infested seeds. Even then he can not 
