12 
SOME INSECTS OTJTTRIOTJS TO TRUCK CROPS. 
At the time when puparia are formed on the leaf surface (see fig. 
2, b) that portion of the leaf is still green, but before the adult hatches 
the infested area usually turns brown, like the larval niines. and the 
first two or three segments of the puparium may be seen protruding 
at the margin of the leaf. TVith the further drying of the leaves 
more segments are exposed, and sometimes the entire puparium is 
brought to view (fig. 
attached by its 
underside to the sur- 
face of the leaf. 
The mines are of 
irregular form, but 
are usually more or 
less rotmded or ob- 
long, although some- 
times irregulary tri- 
angular when found 
in the apex of a leaf. 
The two outer sur- 
faces of the leaves be- 
come separated, and 
the excrement, very 
fine and powdery 
and n e a rl y black, 
can be seen by hold- 
ing the niines to the 
light. The location of 
the larva? can also be 
made out in the same 
manner if. indeed, the 
larva? can not be seen 
on a plain surface. 
The nias^ots usuaUv work somewhat closelv together and the 
puparia also are frequently found placed side by side. Lower leaves 
of plants are more affected than are upper ones, and attack has been 
noticed to be more extensive where plants are grown in shady 
locations. 
A single parasite. SyntomospTiyrum sp.. a chalcidid. determined by 
Mr. J. C. Crawford, has been reared by the writer from this maggot. 
METHODS OF CONTROL. 
Fig. 2. — Parsnip leavei sh : wing location of larva of Acidia fratria in its 
mine at a; of concealed puparia at 6. and of exposed puparium at c 
Drawn from life. (Original.) 
According to the writer's experience, this species shows a fondness 
for plants that have run to seed. Hence it is not desirable to plant 
beds in the vicinity of parsnip or other susceptible crops grown 
