Ernest Edward Austen

“ The tip of the proboscis is armed with a complicated series of chitinous teeth and rasps, by means of which the fly is enabled to pierce the skin of its victim; as usual in Diptera the organ is closed on the upper side by the labrum, or upper lip, and contains the hypopharynx or common outlet of the paired salivary glands, which are situated in the abdomen. The proboscis of tsetse-flies is without the paired piercing stilets (mandibles and maxillae) possessed by other blood-sucking Diptera, such as the female horse-flies and mosquitoes. ”

“ The antennae of Diptera, which are also extremely important in classification, are thread-like in the more primitive families, such as the Tipulidae (daddy-long-legs) , where they consist of a considerable number of joints, all of which except the first two, and sometimes also the last two, are similar in shape; in the more specialized families, such as the Tabanidae (horse-flies) , Syrphidae (hover-flies) or Muscidae (house-flies, blue-bottles and their allies) , the number of antennal joints is greatly reduced by coalescence, so that the antennae appear to consist of only three joints. ”

“ Some species are normally phytophagous, and the vast majority, at any rate, appear to be capable of continuing to exist and reproducing their kind upon a purely vegetarian diet. As a rule the blood-sucking habit is confined to the females, but in the case of a few species it is said to be common to both sexes. The thirst for blood is stimulated by heat, and in temperate climates it is only during hot weather that mosquitoes are troublesome. Some species of mosquitoes, such as the common gnat (Culex pipiens) , are rarely found away from human habitations ”

“ With the exception of a few species from the Solenhofen lithographic Oolite, fossil Diptera belong to the Tertiary Period, during which the members of this order attained a high degree of development. In amber, as proved by the deposits on the shores of the Baltic, the proverbial “fly” is more numerous than any other creatures, and with very few exceptions representatives of all the existing families have been found. ”

“ The impregnated female jigger burrows into the feet of men and dogs, and becomes distended with eggs until its abdomen attains the size and appearance of a small pea. If in extracting the insect the abdomen be ruptured, serious trouble may ensue from the resulting inflammation. At least four species of fleas (including Pulex irritans) which infest the common rat are known to bite man, and are believed to be the active agents in the transmission of plague from rats to human beings. ”

“ As a rule tsetse-flies are most active during the warmer hours of the day, but they frequently bite at night, especially by moonlight. The blood-sucking habit is common to both sexes, and the abdomen, being capable of great expansion, is adapted for the periodical ingestion of an abundant food-supply. ”

“ Under such conditions the deeply-rooted nature of the blood-sucking instinct is most remarkable; for insects whose ancestors for many generations may not have tasted blood will seek for it with the utmost keenness and pertinacity so soon as an opportunity presents itself. ”

“ The footless larvae are elongate, worm-like and very active; they feed upon almost any kind of waste animal matter, and when full-grown form a silken cocoon. The human flea is considerably exceeded in size by certain other species found upon much smaller hosts; thus the European Hystrichopsylla talpae, a parasite of the mole, shrew and other small mammals, attains a length of 51/2 millimetres; another large species infests the Indian porcupine. ”

“ Diptera as an order are probably more widely distributed over the earth’s surface than are the representatives of any similar division of the animal kingdom. Flies seem capable of adapting themselves to extremes of cold equally as well as to those of heat, and species belonging to the order are almost invariably included in the collections brought back by members of Arctic expeditions. ”

“ 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. ”

“ It appears, however, that in this respect the habits of the different species show a certain amount of variation; thus, while G. palpalis exhibits an especial fondness for water and haunts more or less dense cover at the water's edge, recent observations in German East Africa show that G. fusca is in no way connected with water, but is much more frequently encountered at a distance from it. ”

“ The actual piercing organs are the mandibles, while the upper lip or labrum forms a sucking tube. The maxillae are not piercing organs, and their function is to protect the mandibles and labrum and separate the hairs or feathers of the host. ”

“ 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. ”

“ Diptera are divided into some sixty families, the exact classification of which has not yet been finally settled. The majority of authors, however, follow Brauer in dividing the order into two sections, Orthorrhapha and Cyclorrhapha, according to the manner in which the pupa-case splits to admit of the escape of the perfect insect. ”

“ 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 pupa either shows the appendages of the perfect insect, though these are encased in a sheath and adherent to the body, or else it is entirely concealed within the hardened and contracted larval integument, which forms a barrel-shaped protecting capsule or puparium. ”

“ 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. ”

“ The result has been that in subsequent years mosquitoes have been collected, studied and described by naturalists and medical men in all parts of the globe. Nearly 100 genera and about 700 species of mosquitoes are now recognized, but in all probability the total number of species is not less than 1000. ”