occasionally in houses. These include a blue-bottle fly,[4] the black
blowflies,[5] and the green-bottle (fig. 2) flies.[6] They breed in
decaying animal matter.

[Footnote 1: _Musca domestica_ L.]
[Footnote 2: _Stomoxys calcitrans_ L.]
[Footnote 3: _Pollenia rudis_ Fab.]
[Footnote 4: _Calliphora erythrocephala_ Meig.]
[Footnote 5: _Phormia regina_ Meig. and _P. terrae-novae_ Desv.]
[Footnote 6: _Lucilia caesar_ L., _L. sericata_ Meig., and other species
of the genus.]

There is still another species, smaller than any of those so far
mentioned, which is sometimes called the "lesser house fly."[7] This
insect is distinguished from the ordinary house fly by its paler and
more pointed body. The male, which is commoner than the female, has
large pale patches at the base of the abdomen, which are translucent
when the fly is seen on the window pane. These little flies are not the
young of the larger flies. Flies do not grow after the wings have once
expanded and dried.

[Footnote 7: _Fannia canicularis_ L.]

[Illustration: FIG. 1.--The stable fly. Much enlarged.]

[Illustration: FIG. 2.--One of the green-bottle flies (_Lucilia
caesar_). Much enlarged.]

In late summer and autumn many specimens of a small fruit fly, known as
the "vinegar fly,"[8] make their appearance, attracted by the odor of