Minute red mites such as attack the house-flies and other insects sometimes attack adult mosquitoes, but they are rarely very abundant. Parasitic roundworms attack certain species. Others suffer more or less from the attacks of various Sporozoan parasites.
FIGHTING MOSQUITOES
When mosquitoes are bothering us we usually begin by trying to kill the individual pests that are nearest to us. We try to crush them if they bite us; we screen the doors and windows to keep them from the house. In warmer countries the people are a little more hospitable and do not screen the mosquitoes out of the house entirely, but screen the beds for protection at night, and if the mosquitoes get too insistent during the day the bed makes a safe and comfortable retreat. All the mosquitoes in a room may be killed by fumigating with sulphur at the rate of two pounds to the thousand cubic feet of air-space. Pyrethrum is also used largely, but it only stupefies the mosquitoes temporarily instead of killing them. While in that condition they may be swept up and destroyed.
Various substances are sometimes used as repellants by those who must be in regions where the mosquitoes are abundant. With many of these, however, "the cure is worse than the disease." Smudges are often built to the windward of a house or barn-yard and the smoke from a good smoldering fire will keep a considerable area quite free from mosquitoes. The man who can keep himself enveloped in a cloud of tobacco smoke will not be bothered by mosquitoes. Oil of pennyroyal, oil of tar or a mixture of these with olive oil, and various other concoctions are sometimes smeared over the face and hands. These will furnish protection as long as they last. Dr. Smith says that he has found oil of citronella quite effective and of course less objectionable than the other things usually used. Care should be taken not to get it in the eyes. An ointment made of cedar oil, one ounce; oil of citronella, two ounces; spirits of camphor, two ounces, is said to make a good repellant and is effective for a long time.
Fig. 93—Killifish (Fundulus heteroliatus). (From Bull. 47, U.S. Fish Com.)
Fig. 94—Stickleback (Apeltes quadracus). (From Bull. 47, U.S. Fish Com.)