Handbook of Medical Entomology

by William A. Riley; O. A. Johannsen

Fleas are famous for their jumping powers, and in control measures it is of importance to determine their ability along this line. It is often stated that they can jump about four inches, or, according to the Indian Plague Commission Xenopsylla cheopis cannot hop farther than five inches. Mitzmain (1910) conducted some careful experiments in which he found that the human flea, Pulex irritans, was able to jump as far as thirteen inches on a horizontal plane. The mean average of five specimens permitted to jump at will was seven and three-tenths inches. The same species was observed to jump perpendicularly to a height of at least seven and three-fourths inches. Other species were not able to equal this record.

The effect of the bite of fleas on man varies considerably according to the individual susceptibility. According to Patton and Cragg, this was borne out in a curious manner by the experiments of Chick and Martin. "In these, eight human hosts were tried; in seven, little or no irritation was produced, while in one quite severe inflammation was set up around each bite." Of two individuals, equally accustomed to the insects, going into an infested room, one may be literally tormented by them while the other will not notice them. Indeed it is not altogether a question of susceptibility, for fleas seem to have a special predilection for certain individuals. The typical itching wheals produced by the bites are sometimes followed, especially after scratching, by inflammatory papules.

The itching can be relieved by the use of lotions of carbolic acid (2-3 per cent), camphor, menthol lotion, or carbolated vaseline. If forced to sleep in an infested room, protection from attacks can be in a large measure gained by sprinkling pyrethrum, bubach, or California insect powder between the sheets. The use of camphor, menthol, or oil of eucalyptus, or oil of pennyroyal is also said to afford protection to a certain extent.

In the Eastern United States the occurrence of fleas as household pests is usually due to infested cats and dogs which have the run of the house. We have seen that the eggs are not attached to the host but drop to the floor when they are laid. Verrill, cited by Osborn, states that on one occasion he was able to collect fully a teaspoonful of eggs from the dress of a lady in whose lap a half-grown kitten had been held for a short time. Patton and Cragg record seeing the inside of a hat in which a kitten had spent the night, so covered with flea eggs that it looked "as if it had been sprinkled with sugar from a sifter." It is no wonder that houses in which pets live become overrun with the fleas.

One of the first control measures, then, consists in keeping such animals out of the house or in rigorously keeping them free from fleas. The latter can best be accomplished by the use of strong tar soap or Armour's "Flesope," which may be obtained from most druggists. The use of a three per cent solution of creolin, approximately four teaspoonfuls to a quart of warm water, has also been recommended. While this is satisfactory in the case of dogs, it is liable to sicken cats, who will lick their fur in an effort to dry themselves. Howard recommends thoroughly rubbing into the fur a quantity of pyrethrum powder. This partially stupifies the fleas which should be promptly swept up and burned.

He also recommends providing a rug for the dog or cat to sleep on and giving this rug a frequent shaking and brushing, afterwards sweeping up and burning the dust thus removed.

Since the larvæ of fleas are very susceptible to exposure, the use of bare floors, with few rugs, instead of carpets or matting, is to be recommended. Thorough sweeping, so as to allow no accumulation of dust in cracks and crevices will prove efficient. If a house is once infested it may be necessary to thoroughly scrub the floors with hot soapsuds, or to spray them with gasoline. If the latter method is adopted, care must be taken to avoid the possibility of fire.

To clear a house of fleas Skinner recommends the use of flake naphthalene. In a badly infested house he took one room at a time, scattering on the floor five pounds of flake naphthalene, and closed it for twenty-four hours. It proved to be a perfect and effectual remedy and very inexpensive, as the naphthalene could be swept up and transferred to other rooms. Dr. Skinner adds, "so far as I am concerned, the flea question is solved and if I have further trouble I know the remedy. I intend to keep the dog and cat."

The late Professor Slingerland very effectively used hydrocyanic acid gas fumigation in exterminating fleas in houses. In one case, where failure was reported, he found on investigation that the house had become thoroughly reinfested from pet cats, which had been left untreated. Fumigation with sulphur is likewise efficient.

The fact that adult fleas are usually to be found on the floor, when not on their hosts, was ingeniously taken advantage of by Professor S. H. Gage in ridding an animal room at Cornell University of the pests. He swathed the legs of a janitor with sticky fly-paper and had him walk back and forth in the room. Large numbers of the fleas were collected in this manner.