articulated animals, which neither the naturalist nor the physician ought to ignore. Some of these increase with frightful rapidity on the skin which harbours them, and their name alone is sufficient to inspire disgust, if not horror: others live like leeches at the expense of different animals, but without inhabiting them. There are many of these which follow their host everywhere, and which are dreaded not without just reason.
Of this kind are gnats, fleas, lice, bugs, and a great many others, among which we ought not to forget the acaridæ, nor those singular parasites of bats, which bear no slight resemblance to spiders swimming in the midst of the fur. Volumes might be written concerning the organization and the habits of these parasites. These small creatures inspire the naturalist with no more disgust than the earth-worm of our flower-beds, or the salamanders of marshy places. Each one plays its part according to its conformation, and the most abject in appearance is not always the least useful.
We will select among these parasites some two-winged insects, among which there are many which suck blood. Those which are generally called flies are divided into two groups, under the name of Nemocera and Brachycera; many of these live only on blood, and are more terrible than the lion and the tiger; in many countries man can defend himself against those fierce carnivora, but he is there completely powerless and without defence against these insects.
Fig. 7.—Antenna of a Gnat.
Among the Nemocera are found the gnats (Culex
pipiens), those brilliant children of the air, with fine and slender claws, and delicate membranaceous wings, and wearing on their heads feathery antennæ of rare elegance. They are known in the Old as well as in the New World, and in southern regions it is necessary to guard against their nightly attacks by musquito curtains. In the Antilles they bear the name of Maringouins, and in hot countries they are generally known as musquitoes. They are also called gnats, midges, black-flies, zanzare, &c., in different localities, but as may be supposed, these names do not always designate the same insect. The musquitoes of the French colonies are often Simulia. At Madagascar and the Isle of France is found the gnat known by the name of Bigaye.
In Davis’s Straits, in lat. 72° N., Dr. Bessels, on board the Polaris, was obliged to interrupt his observations on account of these insects. A great number of them have been seen up to the 81st degree of latitude. Besides gnats, there were also found Chironomi, Corethræ, and Trichoceræ. As Dr. Bessels was able to save from the Polaris some small collections of insects, we shall soon know the names of the species which live in these high latitudes. It is said that the Esquimaux and the Lapps cover their skin with a coating of grease, not only to lessen the effect of the cold, but to defend themselves from the stings of gnats.
“The gnat is a plague from June till the first frosts,” says Mons. Thoulet, speaking of his abode among the Chippeways. “It renders the country almost uninhabitable; and one is so exhausted by this suffering, which does not cease by night or by day, and by the loss of blood through their bites, that we manage to get through