[Concluded from page 344.] In number of species and individuals, this is an PKteusie order; some are of great service in removing ii:cnnposed matter; others aie so annoying to inn .'i.d beat.r, that Aristotle said, the Hymenoptera Lave thfir tHng in the tail, and the Diptera in the m.ui'h. Few are over an inch long, and must are of n dull color the) iiave two blender spine or-jrir* termed piier?, nt'd kpp.t in constant v -oration. The larva is usually a cylinrinc loot-less grub. The Nemocera have s'xiamted, antennrp, and contain the Harry-lnnr lei and Gnat tribe ; the larva of the former is aquatic, and called Hessian fly or midge, or terrestrial, and termed tailor, crane tly, etc. The Hessipn was first noticed in !7t, on Long Island, and it oviposits in the corolla of wheat, and hence very iuuriou. Gnats have long legs, tuited autenun*, narrow wings, and light bodies ; their larvr breathe through the tail; the females only attack man, penetrating the skin by delicate lancets, sucking the blood by a proboscis, and returning a venomous fluid to mollify its food. Mosquitoes are a larger va-riiy, tLey bear any degree of heat or cold. T.-ieir wings vibrate 3000 times per minute ; In warm climates they are very venomous and powerful, and there is a story that they pierced through Gen. Washington's boots: the horse-chesnut is said to drive them away. Tl e Notacantha are small, but gaily colored. The Tanystoma are carnivorous or insectivorous, and have three-jointed antennse; here belongs that distinguished torment—the gadfly or breeze—of whom even the lion is afraid. Here, too, the female, the blood-sucker; the male living on honey; the athericeral tribe is chiefly herbiverous, but the larvae are voracious for animal matter ; one family resembles the bee, and the caterpillar is called rat-tail. The Fly tribe in Europe numbers over 1700 species; they have winglets, and their larvae are known as maggots; some of which are useful in cleansing, others mine the interior of corn-roots, and breed in some of our eatables; these are the first tormen in Spain, Italy, and the south of France, and so annoy, ing that Foscolo called them one of his three miseries of life. The common house-fly makes 600 strokes per second with its wings, and passes over five feet, and Delisle saw a very minute fly run three inches in a semi-second, making 540 steps. Bot-flies have no mouth, are very hairy, and of a brown color; they are seldom seen, as they live but a short time, but the larviE are always found in living animals, burrowing into the flesh and causing tu- mors. One species is appropriated to man, and penetrates the abdomen. The Pupipara are parasitic, and their eggs are hatched in the matrix, and not excluded till they are pupas The Forest or Spider-fly is small and bristled, and runs like a crab; they have a serrated haustellum like a barbed sting ; they are called ticks or sheep-lice when infesting those animals ; the eggs are laid in the inner edge of the nostrils, whence the maggots ascend and feed in the maxillary and frontal sinuses. A wingless and eyeless species annoys the bee. Those found on bats resemble spiders. XI.—TKIOOPTERA— (Hairy-winged.) This singular group is too anomalous for classification ; the larvae are parasites on the abdomen of bees and wasps, have no feet, no mouth, and absorb juices through the skin ; the insect never exceeds a quarter of an inch in length, and is sexless, takes no nourishment, and lives but a short time ; the greater part of the body is made up of the thorax Instead of anterior wings, there is a pair of nondescript organs, which some call pre-ba-lancers—the only instance where the first pair is undeveloped when there are only two wings present. J. ORTON.