e the most formidable foe of
the hive bee, sometimes producing the well-known disease called
"foul-brood," which is analogous to the typhus fever of man.

[Illustration: 32. Phora and its Young.]

This fly, belonging to the genus Phora (Fig. 32, Phora incrassata; _a_,
larva; _b_, puparium; _c_, another species from Mammoth Cave), is a
small insect about a line and a half long, and found in Europe during
the summer and autumn flying slowly about flowers and windows, and in
the vicinity of beehives. Its white, transparent larva is cylindrical, a
little pointed before, but broader behind. The head is small and
rounded, with short, three-jointed antennae, and at the posterior end of
the body are several slender spines. The puparium, or pupa case,
inclosing the delicate chrysalis, is oval, consisting of eight segments,
flattened above, with two large spines near the head, and four on the
extremity of the body.

When impelled by instinct to provide for the continuance of its species,
the Phora enters the beehive and gains admission to a cell, when it
bores with its ovipositor through the skin of the bee larva, laying its
long oval egg in a horizontal position just under the skin. The embryo
of the Phora is already well developed, so that in three hours after the
egg is inserted in the body of its unsuspecting and helpless host, the
embryo is nearly ready to hatch. In about two hours more it actually
breaks off the larger end of the egg-shell and at once begins to eat the
fatty tissues of its victim, its posterior half still remaining in the
shell. In an hour more, it leaves the egg entirely and buries itself
completely in the fatty portion of the young bee.

The maggot moults three times. In twelve hours after the last moult it
turns around with its head towards the posterior end of the body of its
host, and in another twelve hours, having become full-fed, it bores
through the skin of the young, eats its way through the brood-covering
of the cell and falls to the bottom of the hive, where it changes to a
pupa in the dust and dirt, or else creeps out of the door and transforms
in the earth. Twelve days after, the fly appears.

The young bee, emaciated and enfeebled by the attacks of its ravenous
parasite, dies, and its decaying body fills the bottom of the cell with
a slimy, foul-smelling mass, called "foul-brood." This gives rise to a
miasma which poisons the neighboring brood, until the contagion (for the
disease is ana