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. =SCORPION OR CENTIPEDE STING.= _First Aid Rule.--Squeeze lemon juice on wound._ =SPIDER OR TARANTULA BITE.= _First Aid Rule.--Pour water of ammonia on bite. If patient is depressed, give strong coffee._ =SCORPIONS AND CENTIPEDES.=--These both inhabit the tropics and semitropical regions, and lurk in dark corners and out-of-the-way places, crawling into the boots and clothing during the night. Scorpions sting with their tails, which are brought over the head and back for the purpose, while holding on to the victim with their lobsterlike claws. The poisonous centipede has a flattened brownish-yellow body, with a single pair of short legs for each body segment, and long, many-jointed antennae. The wounds made by either of these pests are rarely dangerous, except in young children and those in feeble health. The stings are usually relieved by bathing with a two per cent solution of carbolic acid, with rum, or with lemon juice. =SPIDERS.=--Many of the tropical spiders bite the human being. Trapdoor spiders are among the commonest of these pests. Their bodies grow to great size, two to two and a half inches long, and are covered with hair giving them a horrid appearance. They live in holes bored in the ground, and provided with a trapdoor contrivance which is closed when the insect is at home. The trapdoor spider resembles the tarantula, by which name it is usually known in Cuba and Jamaica, but is somewhat smaller and commoner. Neither the stings of the trapdoor spider nor true tarantula are usually dangerous although the wounds caused by the bites may heal slowly.