Mosquito Facts

Mosquito, Mosketo, a well-known insect of the gnat family that makes itself a pest by its severe bites. Mosquitoes are constant inhabitants of the warm regions, and during the summer they penetrate even to the arctic regions. In the United States there are about twenty-four species, all belonging to the same family.

The common mosquito may be taken as a type of the entire family. The female pierces the skin and sucks the blood of living animals. The proboscis or beak is needle shaped, slightly enlarged at the end and covered with minute projections, that give it, when magnified, the appearance of a coarse, round file. It is particularly fitted for an instrument of torture and is in principal cause of the irritation that arises from the bites. The proboscis of the male is too weak to pierce the skins of animals, and it feeds on the juices of plants.

The eggs of the mosquito are laid in stagnant fresh water and appear in boat-shaped masses floating on the surface. Each mass is about a quarter of an inch in length and contains from 200 to 400 eggs, set on end in a single layer. In warm weather the eggs hatch in about 16 hours, the larvae appearing as wrigglers. The larvae live in the water, are very active and feed upon minute aquatic organisms. They change to the pupa stage in about seven days under favorable conditions. The pupae float upon the surface and mature in two or three days, when the imago, or perfect insect appears. The life-history of the mosquito during the summer is completed within a period varying from 11 to 14 days, and the insects multiply very fast. During cool weather the period of transition is much longer, and many of the larvae remain torpid through the winter, to become perfect insects the next season.

The common mosquito in the United States, and in temperate latitudes generally, does not transmit disease, but in tropical climates its bite is known to cause elephantiasis. Another species, the Anopheles, transmits malaria, and a third, the Stegomya, propagates yellow fever.

All diseases communicated by mosquitoes are caused by germs. Elephantiasis is caused by a small thread-like worm (Filaria), which lives in the lymphatic vessels of the skin. Its presence causes the skin to become thickened, rough, warty, livid in color and insensible to feeling. The worms multiply and pass from the lymphatics into the blood of the infected individual, where they are found in abundance at night, when the patient is asleep. During the day, however, they do not exist in the blood. The young worms are sucked with the blood of the infected person into the stomach of the mosquito. They remain in the stomach about 17 days, then penetrate the proboscis. When the infected mosquito bites its next victim the worms escape into the lymphatic vessels of the skin, and there they grow to maturity, multiply and produce elephantiasis.

The malaria mosquito can be easily distinguished from the common species by the spots on its wings. The parasite causing malaria is a minute protozoan, or animalcule, consisting of only one cell and know as Hoemamoeba. This parasite infests the red corpuscles of the blood, grows until it occupies the entire corpuscle, then divides into numerous spores, which escape into the liquid plasma of the blood and in turn infest other corpuscles. The spores are liberated from all the corpuscles at the same time, and the liberation produces a paroxysm of chills and fever. There are different varieties of parasites, each having its time for dividing into spores. One variety produces the second brood of spores the second day after the first, so that the malarial paroxysms occur every third day; another produces its second brood in three days and occasions a paroxysm every fourth day, while still another variety causes daily paroxysms. The presence of the malarial parasite in the boll causes the destruction of red corpuscles in large numbers. Standard authorities estimate that a patient of vigorous constitution during the first four days of daily intermittent fever loses 2,000,000 corpuscles per cubic millimeter of blood, and in certain cases the loss of 1,000,000 corpuscles has been verified at the end of 24 hours. In cases having a duration of 20 or 30 days, the number of red corpuscles may be reduced from 5,000,000, the normal number per cubic millimeter, to 1,000,000, or even less.