Fig. 419.
1. Parasite of Turkey; 2. Acarus of common Fowl, under surface; 3. Parasite of Pheasant. (The small circles enclose each about life size.)
The Stylopidæ are remarkable parasites, living upon the bodies of wasps, bees, and bugs, and present a type of structure quite distinct from beetles or the ticks described. The male (Xenos peckii, [Fig. 420]) is a winged insect with coarsely faceted eyes, large fan-shaped wings, extremely small inconspicuous elytra, the two first thoracic rings short, while the metathorax is elongated and covers the base of the abdomen, and the hind legs are placed a long way behind the middle pair. The female, on the other hand, is a grub-like creature, without legs, wings, or eyes; she never leaves the body of her host, and from her eggs active little larvæ develop and get carried into the nests of bees and wasps.
Fig. 420.—Xenos peckii. 1. Male; 2. Female.
Mites are very numerous, differ in form, and are interesting objects under the microscope. The body of the common flea ([Fig. 421]) is divided into distinct segments, those about the thorax being separated. Although apterous, the flea has the rudiments of four wings in the form of horny plates on both sides of the thoracic segments. Its mouth consists of a pair of sword-shaped mandibles, finely serrated; these, with a sharp, penetrating, needle-like organ, constitute the formidable weapons with which it pierces through the skin.
The neck is distinctly separated, and the body covered with scales, the edges of which are beset with short setæ; from the head project a short pair of antennæ, below which are a proboscis and a lance-shaped cutting apparatus. On each side of the head a large compound eye is placed; it has six many-jointed powerful legs, terminating in two-hooked claws; a pair of long hind legs are kept folded up when the insect is at rest, which, in the act of jumping, it suddenly straightens out with great muscular force. The female flea ([Fig. 421]) lays a great number of eggs, sticking them together with a glutinous secretion; the flea infesting the dog or cat glues its eggs to the roots of the hairs. In about four days the eggs are hatched out, and a small white larva or grub is seen crawling about, and feeding most actively. [Plate VI]., No. 141, is a magnified view of one covered with short hairs. After nine or ten days the larva assumes the pupa form; this it retains four days, and in nine days more it becomes a perfect flea. The head of the flea found in the cat ([Fig. 415], No. 3) somewhat differs in form from that of the species infesting the human being; its jaws are furnished with more formidable-looking mandibles, and from between the first and second joints behind the head short strong spines project.
Fig. 421.
1. Female Flea; 2. Male Flea. (The small circles enclose fleas of about life size.)