are coloured dark or shining green. The headless white maggots live in
dung (=House Fly= = _Musca domestica_), in fresh or decaying meat
(=Blue-bottle= = _M. vomitoria_), exceptionally (_M. vomitoria_) in
wounds that are not kept clean, or in the vagina of several domestic
animals. _Remedy_: Compare above (“Flesh Fly”).
The =Flower Flies= (_Anthomyia_).
These are found on flowers, and resemble many common flies in appearance
and colour. The headless white maggots live in dung, also in decaying or
sound parts of plants; a few species may sometimes develop in the one
kind of material, sometimes in the other. _Anthomyia meteorica_ swarms
round the heads of domestic animals, and may even cause inflammation of
the eyes and ears. The =Wheat Bulb Fly= (_Anthomyia coarctata_, about a
quarter of an inch long, yellowish grey, with black hairs) lives as a
larva during winter and spring in the hearts of rye and wheat plants,
the leaves of which become yellow in consequence. During April and the
beginning of May the larvæ quit these plants and become pupæ in the
ground. The second generation can, in like manner, live in various kinds
of summer grain. The =Lupine Fly= (_A. funesta_)—nearly one-fifth of an
inch long, brownish grey (male) or whitish grey (female), with black
legs—digs, when a larva, tunnels in the roots, stems, and seed-leaves of
young lupine plants, causing the root and stem to turn black, and the
seed-leaves to wither. _Preventive Measure_: Early sowing of the
lupines. The =Mangold and Beet Fly= (_A. betæ_), a quarter of an inch
long, yellowish grey, lays its eggs, five to eight in number, in the
young leaves of mangold and beet. The maggots devour the green substance
of the leaf between the two layers of epidermis, so that the leaves die.
In June the maggots creep out of the leaves, and become pupæ in the
soil. The flies quickly escape, and two or three generations follow one
another in the year. As, however, the leaves are now larger, the later
generations only effect a small amount of damage. _Preventive Measure_:
Close sowing of the turnips, so that even if many are killed there will
still be enough young plants. The =Cabbage Root-eating Fly= (_A.
radicum_) and the =Radish Fly= (_A. floralis_) live as fleshy, wrinkled,
dirty white maggots with black dots, in the underground parts of turnip,
cabbage, horseradish, radishes, etc. They lead a similar life to the
=Cabbage Fly= (_A. brassicæ_), the cylindrical, smooth, yellowish white
maggot of which lives in the underground parts of cabbage, turnip, and
rape. The roots attacked swell here and there (Fig. 116), and later on
decay; the leaves of the infested plants first become of a dull leaden
colour and then wither. Entire fields of cabbage, rape, or turnips, are
often destroyed by cabbage fly maggots. The insect passes the winter in
the pupa state; the flies appear early in the spring, and usually twice
more later on. It is therefore most desirable to pull up and burn the
infested plants as soon as possible. A proper rotation of crops should
also be practised. [The =Onion Fly= (_A. ceparum_) maggot feeds within
the bulbs of stored onions. The male fly is grey, the female yellow.]
[Illustration:
FIG. 116.—A turnip infested by the Cabbage Fly: A, swellings; G,
tunnels.
]
The =Cheese Fly= (_Piophila casei_),
one-fifth of an inch long, slender, with a metallic sheen, almost
hairless, black, with dirty yellow legs and wings of glassy clearness.
These small flies abound in front of the windows of places where cheese
is stored; in summer and autumn the shining white maggots, which are
cylindrical in form with tapering ends, and one-third of an inch long,
live in large numbers in old cheese, gnawing it through and through, and
making it dirty. Now and then they spring forwards by bending their
bodies into a circle and suddenly straightening them again. They become
pupæ on the walls or in straw, near the cheeses from which they have
crept out. _Remedies_: Keeping the cheeses clean; mechanical exclusion
(gauze screens outside the windows, enclosure in chests).