Fly

Collier's New Encyclopedia (1921)

in zoölogy, a name applied almost indiscriminately to all insects possessing wings; being often extended to all insects of the sub-order Diptera, and often also restricted to the family Muscidæ. The fly is characterized as possessing a pair of veined and membranous wings, with two movable bodies called balancers (halteres), placed a little behind them. The mouth is formed of between two and six setaceous pieces of scaly texture, and these pieces are either inclosed in a proboscis-like sheath, or covered by one or two laminæ, which form it. The head is globular or hemispherical. The mouth is only formed for transmitting fluids, and is consequently very delicate in structure. The sucker performs the part of a lancet, and pierces the envelope of vegetable or animal fluids, in order to allow of the fluid itself being transmitted up into the mouth of the insect. The antennæ are united in front, and are approximated at the base. Above the true wings of the insect and a little behind them, are the balancers or halteres; these are almost membranous, and are furnished with two little knobs at their extremities, which are capable of dilatation. The legs of this class of insects are long and slender; and the feet, it is well known, are furnished with sk skinny palms, to enable them to stick on glass and other smooth bodies by means of the pressure of the atmosphere. In machinery, that part of a machine which, being put in motion, regulates the rest. În nautical language that part of a compass on which the 32 points are drawn, and to which the needle is attached underneath; the compass-card. In printing, that part of the machinery of a printing press which withdraws the sheet, and lays it aside after the impression is made.