Those marked with an asterisk (*) also carry the larvæ of Filaria bancrofti, as also do Myzorhynchus minutus, Theobald, and Myzorhynchus nigerrimus, Giles.

This genus contains a few large species found either in temperate climates or in hills and mountains of warm climates. The type is the European and North American A. maculipennis.

This genus occurs in Asia, Africa and South America, Europe and East Indies. The type is M. funesta, Giles, found in Central and West Africa. Although structurally there is not much difference between this genus and Anopheles, they differ greatly in appearance, and there are usually a few narrow curved thoracic scales projecting over the head, whilst the wing scales are much smaller in proportion, and the wings more uniformly spotted, always so along the costa. Funesta and lutzii are undoubtedly malaria bearers and also rossii.

A single species only occurs in this genus, N. elegans, James, from India. In this genus, which is near to Myzomyia, the fourth long vein is very near the base of the third, and there are outstanding scales on the prothoracic lobes, and there is a marked tuft of dense scales at the posterior angles of the head.

Two common species only occur in this genus, C. grabhamii, Theob., from Jamaica, and C. mediopunctatus, Theob. (Lutz., ms.), from South America. The chief character is the presence of large black inflated pyriform scales on the wings. The palpi are densely scaled. Neither have been shown to be malaria bearers.

A single species, so far only found in this genus. The basal lobes of the male genitalia of two segments, the prothoracic lobes with dense outstanding scales.

The species, F. pallidopalpi, Theob., occurs in Sierra Leone.

Four species occur in this marked genus—one S. nimba, Theob., from British Guiana and Para, another S. fragalis, Theob., from the Malay States, S. culiciformis, James and Liston, from India, and S. pallida, Ludlow, from India.

The former may be a malaria carrier, for Dr. Low says: “Malarial fever is got amongst the Indians and often of a severe type. In that connection it is interesting that in the interior, at a place called Corato, I got an entirely new Anopheles in large numbers.” The genus is easily told by its unornamented wings, flat head scales, mammillated prothoracic lobes and long thin legs.

Forty-four species come in this genus, of which Anopheles costalis, Loew, is the type.

This genus is found in Africa, India, Europe and in Australia. Three species are proved malaria bearers, namely, P. costalis, Loew, P. chaudoyei, Theob., and P. superpictus, Grassi. Members of this genus can be told by having narrow curved thoracic scales, hairy abdomen, and much-spotted wings.

In this genus the thorax has distinct, narrow curved scales, and the abdomen is hairy, the wing scales broad and lanceolate, and the head with broad scales not closely appressed, but not forked or fimbriated.

Five species are known: lutzi, Cruz; parva, Chagas; nigritarsis, Chagas; tibiomaculata, Neiva; gilesi, Neiva; and nigra, Theobald. They are all recorded from Brazil, and nigra also from Mexico.

A single marked species from the Brazils. The thorax has piliform curved scales, and some narrow curved and flattened ones on the sides. Abdomen pilose, except the last three segments which are scaled. No tufts of scales on posterior femora.

Allied to Lophoscelomyia, but at once told by the absence of scale tufts on the hind femora. M. lutzi, Cruz, Brazil.

A very marked genus in which the hairy abdomen has very long, dense, hair-like, apical, scaly tufts to the segments. A single species only so far known, C. implexa, Theobald, from Africa (Uganda, Sudan, etc.).

A single species only, from the Federated Malay States. The hind femora have dense, apical scale tufts; the thorax long, hair-like curved scales; abdomen pilose, except the last two segments which are scaly; wings with broad, blunt, lanceolate scales.

Two species only occur, found in South America. The thorax and abdomen have scales and hairs respectively, as in Pyretophorus, but the abdomen has in addition prominent lateral apical scale tufts to the segments and a scaly venter. Wings with membrane tinged in patches and wing scales bluntly lanceolate and very dense. The type is A. maculipes, Theob. found in Trinidad and Brazil; A. pseudomaculipes, Cruz, also in Brazil.

A very marked genus of large, dark, densely scaled species, found in Europe, Asia, Africa and Australia. The thorax with hair-like curved scales; the abdomen with ventral and apical scales, and a median ventral apical tuft, and with very densely scaled palpi in the female, and densely scaled proboscis. It seems to be mainly an Asiatic and East Indian genus, but three species occur in Africa and one in Australia. They are mostly sylvan species and bite severely.

Fourteen species are known. Five are malaria carriers (vide list, p. 566).

A group of small, closely allied species found in Asia, Africa and Australia, twelve out of the twenty species coming from India.

The thorax is covered with narrow curved and spindle-shaped scales, abdomen with small, flat or narrow curved dorsal scales, especially on the apical segments or in patches; the legs are always banded or spotted with white, and the tarsi have as a rule one or more pure white segments. (This banding and spotting is of no generic value, however.)

The species show considerable seasonal variation. The type of the genus is N. maculatus, Theobald.

Three are malaria carriers (vide list, p. 566).

Very marked Anophelines, with densely scaly abdomens, the scales irregularly disposed on the dorsum and forming dense lateral tufts; thorax with flat spindle-shaped scales; palpi densely scaled and also the wings.

The type of the genus is the African C. pharoensis, Theob. It is represented in Asia by C. kochii, Dönitz; in West Indies and South America by C. argyrotarsis, Desvoidy, and C. bigotii, Theob.; in Africa by C. squamosa, Theob., etc.

C. argyrotarsis, Desvoidy, and C. albimana, Wiedemann, are undoubtedly malaria bearers.

Allied to Cellia, but has no lateral scale tufts. Three species recorded from India.

This genus has the thoracic scales hair-like, except a few narrow curved ones in front; abdominal scales long, broad and irregular.

A single species, K. boliviensis, Theob. from Bolivia.

The thorax has narrow hair-like curved scales and some broad straight scales; others spatulate on the sides. Abdomen with fine hairs, except the last three segments which are scaly. Tufts of scales on the hind femora. Wing scales lanceolate.

The type is M. lutzi, Cruz, from Brazil.

This genus can at once be told by the antennal segments having many dense scaly tufts. Type, C. fajardoi, Lutz, from Brazil.

The antennæ in this genus have outstanding scales on the second segment, more appressed ones on the first. At least one abdominal segment with long, flat, more or less spatulate scales. Type, C. lineata, Ludlow, from Philippine Islands.

At once told by the first submarginal cell being very small. Type, B. gracilis, Theob. from New Guinea.

Three genera occur in this marked sub-family; they are the largest of all mosquitoes, and are very brilliantly coloured, and many have tail fans. They occur in North and South America, Asia, Africa, and Australia. The long curved proboscis is very marked. They are usually spoken of as elephant mosquitoes; some are vicious blood-suckers at times.

The three genera tabulate as follows:—

All large brilliant mosquitoes with long palpi in both sexes and, as a rule, with a caudal fan of scales; the proboscis is long and bent. They are all sylvan species, and are not so far recorded as biting man.

Differs from the former genus in that the female palpi are short. The palpi may have one, two or three minute terminal segments. Banks’s genus Worcesteria has three.

The elephant mosquito of India (T. immisericors), Walker, bites very severely. They are sylvan species.

This genus is so far confined to Australia, West and Central Africa, India, East Indies and Malay Peninsula. They are all large mosquitoes, easily told by the whole body being more or less covered with long twisted scales, giving them a mouldy appearance, and the legs densely scaled with outstanding scales; the wings with large parti-coloured scales. The Australian M. alternans, Walker, occurs in larval form both in fresh and salt water. The adults bite man.

This genus is confined to the Americas and the West Indies. Several species exist which can easily be told from Mucidus by the absence of long twisted scales and the narrower wing scales. The legs are densely scaled and the thorax ornamented with flat spindle-shaped scales.

P. ciliata, Robineau Desvoidy, occurs in both North and South America, and bites man.

Hind legs only densely scaled; some of the hind tarsi are always white. The venation is as in Culex. The abdomen is metallic and iridescent. They all bite man and occur only in the Americas and West Indies.

This, the most important genus in the Culicinæ, can be told by the head and scutellum being clothed with flat scales and the thorax with narrow curved ones.

About forty species are known in this genus, occurring in Southern Europe, Asia, Africa, Australia, the Americas, East and West Indies, and on most oceanic islands. Many of them seem to be vicious blood-suckers. They are mostly black and white mosquitoes, and several seem to go by the name of tiger mosquitoes. The genus contains the yellow fever mosquito (S. fasciata, Fabricius), the only one that need be dealt with in detail here. The chief known species tabulate as follows:—

This insect, which is the proven carrier of yellow fever, is commonly called the tiger, brindled, spotted day or striped mosquito. It is also referred to by some writers as S. calopus, Meigen. It is subject to considerable variation in colour, but the thoracic markings are generally very constant. The general colour is almost black to deep brown, the head with a median white area, white at the sides and in front around the eyes; the thorax has two median parallel yellow lines, a broad curved silvery one on each side and white spots at the sides; the scales on the intervening spaces of the thorax are brown. The dark abdomen has basal white bands and basal white lateral spots. The dark legs have basal white bands, the last segment of the hind legs being all white except in a variety from South America and the West Indies (luciensis), which has the tip of the last hind tarsal dark. The abdomen may also vary in colour, some having pale scales over most of the surface (queenslandensis).

The food of the adult female consists mainly of man’s blood, but she will also feed on dogs and other animals. The male has been said to bite, but such is very unusual. This mosquito bites mainly in the daytime up till about 5 p.m.

The adults breed the first day after emergence. They may live a considerable time, Bancroft having kept females for two months in confinement. The ova are laid separately, often in chains; they are black, oval, with a reticulated membrane outside, some of the reticulated cells containing air. They may hatch in from six to twenty hours, the larval stage nine days, the pupal stage three; thus the whole cycle may be completed in from twelve to thirteen days. The ova when dry can remain undeveloped for a considerable time. The larvæ are greyish-white, with short, thick siphon, and feed at the bottom of the water, only coming to the surface now and again to breathe. This is almost entirely a domesticated gnat, seldom being found far from man’s habitations. Its larvæ occur in such small collections of water as old sardine tins, jam-pots, calabashes, puddles, barrels, wells—in fact, wherever water is held up, even to the gutters of houses. Not only are they found breeding on land, but also on board ship, although they prefer artificial collections of water. They may also breed in larger natural collections.

This insect is easily transported by steam and sailing ships and by train, and this doubtless explains its very wide distribution. The adults may live for fifty days, and it is on this account and their frequent occurrence on ships that danger lies in regard to the Panama Canal. An infected insect may leave that endemic centre of yellow fever and live until the vessel arrived at the Philippine Islands and fly ashore, and so introduce the disease for the native fasciata possibly to spread.

Roughly the distribution of this pest is as follows: Africa from South to North, but especially along the coast and up the Nile. In Asia, in India, Ceylon, Burma, Siam, along the ports of the Malay Peninsula, in French Cochin China, Philippine Islands, the Andaman and Nicobar Islands, Japan, Malay Archipelago, and East Indies, Turkey in Asia, Arabia and Palestine.

In Australia it occurs in Queensland, New South Wales, Victoria and South Australia.

In Europe in Italy, Spain, Portugal, Greece, in the Mediterranean Islands.

In South America, Central America, Mexico, North America, and the West Indies it is very abundant, and it also is found in the Bahama Islands, Fiji, Sandwich Islands, Samoa, the Azores, Teneriffe and Santa Cruz, Pitcairn Islands and Bermuda.

For a full account of its distribution the reader is referred to the following: “The Distribution of the Yellow Fever Mosquito (Stegomyia fasciata, Fabricius) and General Notes on its Bionomics;” “Mém. 1^er Congrès international d’Entomologie, 1911, ii, pp. 145–170, F. V. Theobald.” In addition to being the yellow fever carrier, it is supposed by Wenyon to be the intermediate host of the parasite of Bagdad sore.

A vicious biter, found in India, China, Malay, East Indies, and Ceylon. The thorax has one median silvery stripe, and so can easily be told from S. fasciata.

A very similar species occurs in Fiji, but can be told by the pleuræ having white lines, not spots (S. pseudoscutellaris, Theobald). It is the intermediate host of filaria in Fiji (Bahr).

A number of nearly allied genera occur here (vide synoptic table).

Includes several large Culicines, of which T. annulata, Meigen, is the type. The wings are usually spotted (annulata, incidens, etc.), but may be nearly plain (spathipalpis). The males have the palpi swollen apically, and the females have long five-jointed palps.

Several of these are vicious biters.

This large gnat (6 mm. long) can be told by its wings having five large spots of dark scales and by its legs having broad basal white bands to the tarsi. The larvæ occur in rain barrels and small pools. It is essentially a domestic form, occurring in houses and privies. Its distribution is Europe generally and North America. The bite is very severe, and in some districts gives rise to painful œdema.392

Theobaldia spathipalpis, Rondani, occurs in Italy, Mediterranean Islands, Palestine, the Himalayas, Khartoum, and in South Africa. It is about the same size as T. annulata, but is yellowish-brown in colour, with striped thorax and mottled and banded legs. It occurs in privies and bites very severely.

This large genus still contains many forms which should be excluded. The species normally have narrow curved median head-scales, and similar ones on the scutellum; the female palpi are shorter than in the former genus and the male palpi are pointed; the lateral vein-scales are narrow and linear.

The type is Culex pipiens, Linn., the common gnat of Europe. The thorax is covered with narrow curved golden-brown scales, the abdomen has basal pale bands to the segments and the legs and proboscis are unbanded. The stem of the first submarginal cell is always less than one-fifth the length of the cell. It lays its eggs in rafts in water-butts, etc., and even in the foulest water. They are first deposited in England in June and July, and again soon after hatching in August. In some districts this gnat bites man viciously, in others not at all.

The common tropical gnat (Culex fatigans, Wied). This resembles the European Culex pipiens, but can always be told by the stem of the first submarginal cell always being much longer than it is in C. pipiens. This is one of the species that has been proved to transmit filariæ to man, etc. Varieties of it occur in almost every country between 40° N. and S., having a very similar range to S. fasciata. In all countries it appears to be connected with the transmission of Filaria bancrofti, and it is also said to carry the micrococcus of dengue fever.

This genus is composed of eight species, most of which are small black gnats which bite viciously and which occur in swamps and jungles. They can at once be told from Culex by the veins of the wings having dense broadened scales on their apical areas and along the upper costal border. The femora and apices of the tibiæ are swollen.

The black mosquito, Melanoconion atratus, Theob. This small gnat is a very troublesome pest in swamps in the West Indies. The female bites both by day and by night, and the bite causes severe irritation. The larvæ live in permanent ponds. It is almost black in colour, but sometimes presents a dull coppery sheen; each segment has small lateral basal white spots. Length 2·5 to 3 mm.

It occurs in Para and British Guiana as well as in the West Indies.

Ordinary mosquito netting is no use for keeping off this pest.

Allied to Culex, but separated by the wings having short fork-cells, mottled scales, the median ones thick and also some of the lateral ones short and broad; the last two joints of the male palps are very slightly swollen. The eggs are laid singly, not in rafts, and the larvæ have short, thick siphons. Ten species occur and are found in Europe, North America, West Indies and Natal. G. dorsalis, Meigen, bites severely in Europe. G. sollicitans, Walker, is a great scourge along the New Jersey Coast and at Virginia summer resorts and in Florida. It breeds in brackish water and is the most common mosquito of the Atlantic seaboard.

Differs from the former in having the whole wing veins clothed with dense, broadish elongated scales. They occur in South America (T. fasciolatus, Arri.), in Africa (T. tenax, Theob.), in Europe (T. richardii, Ficalbi). The latter bites very severely.

A very marked genus, easily told by the broad asymmetrical wing scales. It occurs in Africa (T. africana and T. major, Theob.); in Asia (T. uniformis, Theob.; T. annulipes, Walker, etc.) and in Australia (T. australiensis); in the Americas and West Indies (T. titillans, Walker). The eggs (fig. 395, d) are peculiar in form and are laid separately; the larva has not been described; the pupa has long curved siphons. They mostly occur along rivers, in swamps and forests, and bite very severely. They also enter houses (T. titillans). T. uniformis is most troublesome during the rains. The saliva is strongly acid. Both these species carry the larvæ of Filaria bancrofti.

Bright yellow or yellow and purple mosquitoes, with rather dense wing scales. Numerous species occur in Africa (aurites, annettii, fuscopennatus, etc.), others in India, Australia and South America.

Low found filariæ in the thoracic muscles of fuscopennatus in Uganda.

Several of the Ædeomyina bite, especially the small Uranotænias. They are all sylvan species, seldom entering houses. They need not, therefore, be referred to here.

For full details of the Culicid genera and species the reader is referred to my monograph393 and other works mentioned below.

Other nematocerous flies are midges, daddy-long-legs and sand-flies. The ones which cause annoyance to man besides Culicidæ are the following:—

Sand-flies (Simulidæ), certain midges (Chironomidæ), and a few owl midges (Psychodidæ).

The Nematocera have long thread-like jointed antennæ and their pupæ are, as a rule, naked; the larvæ have a distinct head and can thus be told from the next section (Brachycera).

This family consists of a single genus, Simulium, Latreille, which Roubaud has recently divided into two sub-genera called Pro-Simulium and Eu-Simulium. These insects, which are frequently spoken of as sand-flies, are found in all parts of the world; they are all small insects varying from 1·5 to 3 mm. The females are very bloodthirsty, but the males appear to be incapable of sucking blood.

The head sunk under the humped thorax; antennæ short, straight; palpi short and broad, of four segments, bent; wings broad and in some iridescent, legs stout. The male has holoptic eyes, whilst in the female they are small and widely separate. The sucking proboscis is short. The thorax and abdomen are clothed with short hairs which may form spots and markings; these are golden, silvery, grey, or brownish. In the sub-genus Pro-Simulium the second segment of the hind tarsi in both sexes is elongate, linear, and without a basal notch; in Eu-Simulium it is short, curved, and dorsally notched at the base.

Simulidæ often occur in swarms, and attack not only man but cattle, horses, and poultry. In some districts they are more annoying than mosquitoes.

Their life-cycle has been most completely worked out by King, in Africa.

The larvæ and pupæ occur in swiftly flowing water, by waterfalls, in rapids, etc. The ova are laid in gelatinous masses on plants or rocks close to or overhanging the water. The larva is cylindrical, enlarged posteriorly, where it is provided with a sucker, by means of which it attaches itself to a rock, water weeds, debris, etc.; anteriorly it has a proleg close behind the head on the lower surface. The head is dark and chitinous. The respiration takes place by means of branched tracheal gills which protrude from the dorsal surface of the last body segment; they are retractile. The colour varies from deep green to yellow or almost black. Their food consists of algæ and other organisms in the water brought to their mouth by two fan-like organs placed on the head. The larvæ can crawl from place to place by means of the thoracic proleg; they occur in masses, usually in a more or less erect attitude. A network of threads is spun on their support, by means of which King tells us “they are enabled to maintain their position against the strongest current; frequently they will leave their support and let themselves out into the stream anchored by threads of silk and enabled by them to return.”

When full fed the larva spins a pocket-shaped cocoon on the support, within which it pupates. The pupa is motionless and has a pair of branched spiracles projecting from behind the head. When the adult emerges, a bubble of air collects around it, and in this it floats to the surface and at once takes wing. The European species take a month to complete larval life, a week being spent in the pupal stage. The flies are most restless, and even when stationary continually move their legs about like feelers. Sometimes the swarms consist entirely of females, sometimes early in the season mostly of males.

The females pierce the skin of humans on tender spots, such as ears, the forehead, around the eyes and nose, and crawl into the cavities. They are quite harmless at night, mainly attacking about sunrise and sunset. Some crawl up the arms and legs and down the neck, and leave behind little red weals which itch intensely (S. damnosum, Theob.), and blood may flow freely from the wounds.

The following are some of the worst species:—

Simulium columbaschensis, the “Kolumbatz fly,” which abounds in the damp marshy lands along the Danube, and is a great plague to man and beasts in Hungary, and is also abundant in Austria and Moravia, and is most numerous after inundations from the Danube. They sometimes appear in such swarms that it is impossible to breathe without getting them into one’s mouth. There are instances of children being killed by these flies when left on the ground by their mothers when working in the fields.

S. damnosum, Theob. This occurs throughout Equatorial Africa and is known as the “jinja fly” in Uganda, the “fouron” in the French Congo, the “kilteb” in the Sudan. It is a most vicious biter, and in some parts occurs in “belts”; Dr. Christy found one such extending from the shores of the Victoria Nyanza northwards along the right bank of the Nile for twelve or fifteen miles or more, and perhaps three or four miles wide. In this area the flies swarm in millions at certain seasons, so much so that the natives have to leave their plantations. The bite causes a weal, marked by a drop of blood.

S. griseicollis, Becker. The so-called “nimitti” occurs in Upper Egypt and the Anglo-Egyptian Sudan. It lives near the river and is not found more than half a mile from it. Human beings are bitten on the face and hands, animals in the region of the pudenda.

S. latipes, Meigen. This is a European species, also found in Natal.

S. wellmanni, Roubaud. The “ohomono” of Angola, where it bites viciously and is dreaded by the naked porters.

S. buissoni, Roubaud. Occurs in abundance in the Marquesas Islands. It has been suggested that this species may help to propagate leprosy.394

A large number of these insects have been described by Lutz in Brazil.395

A Simulium sp. (?) is very harmful to poultry in Cape Colony.396

In America, Simulidæ are most annoying. One, S. meridionale, Riley, also known as the turkey gnat in the Mississippi Valley, has been supposed to be the carrier of chicken cholera; anyhow, it has caused the death of thousands of chickens and turkeys in Virginia annually.397

In Mexico Townsend found a Simulium which was named S. occidentalis, which caused great annoyance to man, many people being so susceptible to them as to preserve through the gnat season a chronic inflammation of the exposed parts of face and neck, resulting from the repeated bites giving rise to sores.398

Men and horses have been partially incapacitated by the bites of sand-flies or Simulium in a Hampshire wood (Cantlie, Brit. Med. Journ., April 28, 1900, v, No. 2,052, p. 1023).