Page:EB1911 - Volume 18.djvu/934

 as the common gnat (Culex pipiens), are rarely found away from human habitations; others seldom or never enter houses, but are met with either in more or less open country, or in the recesses of forests and woods. In Europe and North America the continued existence of species is ensured by the hibernation of impregnated females, or else the winter is passed in the egg or occasionally in the larval state. In tropical climates with a well-marked dry season mosquitoes pass into a semi-dormant condition during the period when there is little Water in which to deposit their eggs. Culicidae are by no means confined to low-lying districts, and have even been met with in the Himalayas at an altitude of 13,000 feet. The wide distribution of certain species is undoubtedly attributable to the agency of ships and trains; under natural conditions mosquitoes seldom travel far from their breeding grounds, although the powers of flight of some species are greater than has been supposed. The preliminary stages of all mosquitoes are passed in water, either fresh or salt, stagnant or slightly moving. The nature of the breeding-place varies greatly according to the species, and while many of the mosquitoes that infest houses will breed even in the smallest accidental accumulation of water such as may have collected in a discarded bottle or tin, the larvae of other species less closely associated with man are found in natural pools or ditches, at the margins of slow-moving streams, in collections of water in hollow trees and bamboo-stumps, or even in the water-receptacles of certain plants. The eggs are usually deposited on the water itself, and while in the case of certain species, such as Culex pipiens or the widely distributed C. fatigans, they are agglutinated together in masses known as “boats” or “rafts” containing from 50 to 400 ova, those of others, such as the Anophelinae and many Culicinae (e.g. Stegomyia calopus), are laid separately. The larvae are active and voracious little grub-like creatures (known in the United States as “wrigglers”), with large heads and jaws provided with a pair of brushes, which sweep food-particles into the mouth. Their food consists of minute animal and vegetable organisms,

algae, and probably decaying vegetable matter; they are often cannibals, and feed on their own species. The larvae of species belonging to the Culicinae have a prominent breathing tube, or respiratory siphon, on the penultimate (eighth) abdominal segment, and when taking in air hang head downwards (often nearly vertically) from the surface film. Larvae of Anophelinae, on the other hand—which are grey, green or brown in colour, and often extremely difficult to see—have no respiratory siphon and lie almost horizontally at the surface; they frequently appear as though anchored by the tail to a weed or other object, and possess the curious faculty of completely rotating the head so as to browse on the surface film. Mosquito pupae are comma-shaped (see fig. 1), and breathe by means of a pair of respiratory trumpets on the thorax.

The majority of mosquitoes are dull in hue, but certain species are brilliantly coloured or conspicuously banded or spotted with white. The Anophelinae have narrow bodies, and generally spotted wings, and when at rest keep body and proboscis in a straight line, often at a considerable angle with the supporting surface; in this way they can be distinguished from Culicinae, which have a humped-up thorax with which the proboscis forms an angle, and in the resting position keep the body parallel to the support.

The disseminators of malaria are exclusively Anophelinae, but even among these it is only certain species that are dangerous, since the others appear to be incapable of acting as hosts of the parasites. Stegomyia calopus, on the other hand, a very widely distributed species and the almost certain carrier of yellow fever, belongs to the Culicinae. In the case of filariasis due to Filaria bancrofti, which is common throughout the Tropics, the embryos of the parasite are disseminated by various Culicinae and Anophelinae (Culex pipiens in Queensland; C. fatigans in the West Indies; Myzomyia rossii in India; Pyretophorus costalis in a large portion of tropical Africa; &c.). Six or seven species of mosquitoes are also the intermediate hosts of Filaria immitis, which infests the right auricle and pulmonary artery of the dog, and occurs throughout the tropics, in southern Europe, the United States of America, and elsewhere. There is reason to believe that malaria, yellow fever and filariasis are not the only diseases disseminated by mosquitoes.

MOSQUITO COAST AND RESERVE ( or ), a division of the republic of Nicaragua, officially styled the department of Zelaya. Pop. (1905), about 15,000. Although its name is sometimes applied to the whole eastern seaboard of Nicaragua—and even to Mosquitía in Honduras, i.e. the coast region as far west as the Rio Negro or Tinto—the Mosquito Coast is more accurately defined as a narrow strip of territory, fronting the Caribbean Sea, and extending from about 11° 45′ to 14° 10′ N. It stretches inland for an average distance of 40 m., and measures about 225 m. from north to south. In the north, its boundary skirts the river Wawa; in the west, it corresponds with the eastern limit of the Nicaraguan highlands; in the south, it is drawn along the river Rama. The chief towns are Bluefields or Blewfields, Magdala on Pearl Cay, Prinzapolca on the river of that name, Vounta near the mouth of the Cuculaia, and Carata near the mouth of the Wawa. Bluefields (pop. about 2000) is the capital and the largest town. It is the seat of a Moravian mission, and has a good harbour, with regular steamship services to Greytown in Nicaragua, and to New Orleans. It exports bananas and other fruit.

The Mosquito Coast is so called from its principal inhabitants, the Misskito Indians, whose name was corrupted into Mosquito by European settlers and has been entirely superseded by that form except in the native dialects. The Mosquito Indians, of whom there are several tribes, are an unusually intelligent people, short of stature and very dark-skinned. Their colour is said to be due to intermarriage with shipwrecked slaves.

The first white settlement in the Mosquito country was made in 1630, when the agents of an English chartered company—of which the earl of Warwick was chairman and John Pym treasurer—occupied two small cays, and established friendly relations with the Indians. From 1655 to 1850 Great Britain claimed a protectorate over the Mosquito Indians; but little success attended the various endeavours to plant colonies, and the protectorate was disputed by Spain, the Central American republics, and the United States. The opposition of the United States was due very largely to the fear that Great Britain would acquire a privileged position in regard to the proposed interoceanic canal. In 1848, the seizure of Greytown (San Juan del Norte).