The eggs or "nits" are next to be attacked with vinegar, which is sponged on the hair and the fine-tooth comb plied daily for a week. The remaining irritation of the scalp can be cured by washing the head daily and applying sweet oil.
A simpler plan consists of drenching hair and scalp twice with cold infusion of (poisonous) larkspur seed, made by steeping for an hour an ounce of the seed in six ounces of hot water.
This treatment will destroy both insects and eggs. After twenty-four hours the hair and scalp must be shampooed with warm water thoroughly.
CLOTHES LICE.—These insects are a trifle larger than the head lice, being one-twelfth to one-eighth inch long, of a dirty, yellowish-gray color, and only infesting the most filthy people. The lice are generally only seen on the clothes, where they live, coming out on the body only to feed. The visible signs on the body are varying degrees of irritation from redness to ulceration, due to scratching. The treatment is simply cleanliness of the body and clothes.
CRAB LICE.—The crab louse or "crab" inhabits the skin covered by hair about and above the sexual organs most frequently, and from thence spreads to the hairy region on the abdomen, chest, armpits, beard, and eye lashes. Itching and scratching first call attention to the presence of the parasites, which are even more troublesome than the other species.
Application of kerosene to the part is sufficient to kill the lice, but this treatment must be repeated several times at intervals of a week, in order to kill the parasites subsequently hatched.
FLEA.—Flea bites are recognized by the itching caused by the poison introduced by the insect, and by points of dried blood surrounded for a little while by a red zone. In the case of children and people with delicate skins, red or white lumps appear resembling nettlerash. Generally the skin is simply covered with minute, red points, perhaps raised a little by swelling above the surface, and when very numerous may remotely resemble the rash of measles. Fleas, unlike lice, do not breed on the body, but as soon as they are satiated leave their host. Their eggs are laid in cracks in floors, on dirty clothes and similar spots, and it is only the mature flea which preys upon man. The human flea may infest the dog and return to man, but the dog flea is a distinct species, and never remains permanently on the human host. For these reasons it is not difficult to get rid of fleas after they have attacked the body, unless continually surrounded by them.
JIGGER OR SAND FLEA.—Also called chique, chigo, and nigua. It is common in Cuba, Porto Rico, and Brazil. About one-half the size of the ordinary flea, it is of a brownish-red color with a white spot on the back. The female lives in the sand and attacks man, on whom she lives, boring into the skin about the toe nail, usually, and laying her eggs under the skin, which gives rise to itching at first and then violent pain. The insect sucks blood and grows as it gorges itself, producing a white swelling of the skin in the center of which is seen a black spot, the front part of the flea. The flea after expelling its eggs drops off and dies. People with habitually sweaty feet are exempt from attacks of the pest.
Unless the flea is unattached, one must either wait until the insect comes away of its own free will, or remove it with a red-hot needle in order to destroy the eggs. The negroes peel the skin from the swelling with a needle and squeeze out the eggs. Ordinarily the bites do no permanent injury, but occasionally if numerous, or if the insect is pressed into the skin in the efforts to remove it, or if sores resulting from bites are neglected, then violent inflammation, great pain, and even death of the part may result. Sound shoes and a night and morning inspection of the feet will protect against the inroads of the sand fleas.
FLIES.—The common housefly does not bite, but is constantly inimical to human health by conveying disease germs of typhoid fever, cholera, and other disorders from bowel discharges of patients suffering from these diseases to articles of food on which the insects light. Flies have been a fruitful source of sickness in military camps, as evidenced in the recent Spanish-American and Anglo-African campaigns. The bites of the sandfly, gadfly, and horsefly may be both relieved and prevented by the same means recommended in the case of mosquitoes for these purposes.