n the
leaf, or burrowing in seeds or under the bark of plants. We have often
noticed blister-like swellings on the bark of the willow, which are
occasioned by a cylindrical, short, fleshy larva (Fig. 88_a_, much
enlarged), about a line in length, which changes to a pupa within the
old larval skin, assuming the form here represented (Fig. 88_b_), and
about the last of June changes to a small black fly (Fig. 88), which
Baron Osten Sacken refers doubtfully to the genus Lonchaea.

[Illustration: 86. Willow Blister fly.]

The Apple midge frequently does great mischief to apples after they are
gathered. Mr. F. G. Sanborn states that nine-tenths of the apple crop in
Wrentham, Mass., were destroyed by a fly supposed to be the Molobrus
mali, or Apple midge, described by Dr. Fitch. "The eggs were supposed to
have been laid in fresh apples, in the holes made by the Coddling moth
(Carpocapsa pomonella), whence the larvae penetrated into all parts of
the apple, working small cylindrical burrows about one-sixteenth of an
inch in diameter." Mr. W. C. Fish has also sent me, from Sandwich,
Mass., specimens of another kind of apple worm, which he writes has been
very common in Barnstable county. "It attacks mostly the earlier
varieties, seeming to have a particular fondness for the old fashioned
Summer, or High-top Sweet. The larvae (Fig. 89 _a_) enter the fruit
usually where it has been bored by the Apple worm (Carpocapsa), not
uncommonly through the crescent-like puncture of the curculio, and
sometimes through the calyx, when it has not been troubled by other
insects. Many of them arrive at maturity in August, and the fly soon
appears, successive generations of the maggots following until cold
weather. I have frequently found the pupae in the bottom of barrels in a
cellar in the winter, and the flies appear in the spring. In the early
apples, the larvae work about in every direction. If there be several in
an apple, they make it unfit for use. Apples that appear perfectly sound
when taken from the tree, will sometimes, if kept, be all alive with
them in a few weeks." Baron Osten Sacken informs me that it is a
Drosophila, "the species of which live in putrescent vegetable matter,
especially fruits."

[Illustration: 89. Apple Worm and its Larva.]

[Illustration: 90. Parent of the Cheese Maggot.]

[Illustration: 91. Pupa case of Wine-fly.]

An allied fly is the parent of the cheese maggot. The fly itself
(Piophila casei, Fig. 90) i