_Phorbia ceparum_ (Meig.)


Early in June a somewhat hairy fly, Fig. 9, may be seen flying about,
and depositing its eggs on the leaves of the young onion plants, near
the roots, Fig. 10.

[Illustration: FIG. 9.]

Dr. Fitch describes this fly as follows: "It has a considerable
resemblance to the common house fly, though when the two are placed
side by side, this is observed as being more slender in its form. The
two sexes are readily distinguished from each other by the eyes, which
in the males are close together, and so large as to occupy almost the
whole surface of the head, while in the females they are widely
separated from each other. These flies are of an ash gray color, with
the head silvery, and a rusty black stripe between the eyes, forked at
its hind end. And this species is particularly distinguished by having
a row of black spots along the middle of the abdomen or hind body,
which sometimes run into each other, and then forming a continuous
stripe.

"This row of spots is quite distinct in the male, but in the female is
very faint, or is often wholly imperceptible. This fly measured 0.22
to 0.25 inch in length, the females being usually rather larger than
the males." The eggs are white, smooth, somewhat oval in outline, and
about one twenty-fifth of an inch in length. Usually not more than
half a dozen are laid on a single plant, and the young maggot burrows
downward within the sheath, leaving a streak of pale green to indicate
its path, and making its way into the root, devours all except the