These may be of several types, of which the following are most common: (1) Hair like curved scales; these are finer than narrow curved scales and may form a dense felt work over the mesothorax. (2) Narrow curved scales; these may occur over all the mesothorax and scutellum. (3) Spindle shaped scales; they lie scattered about and do not form a complete covering. (4) Flat scales, like those on the head. They occur, for instance, on the scutellum, in the genus Stegomyia. (5) Long twisted scales expanded at the end in the genus Mucidus.
These, in the vast majority of the Culicidce, are flat scales. In the Anophelince, except in the genus Aldrichia, they are, however, almost entirely absent.
The veins (except the cross veins) have-(1) flat scales, arranged in a double row along each vein, while generally there are also (2) lateral scales along each vein. These vary much in shape, and may be-(1) Broad, asymmetric, flat scales-e. g., in Mansonia and Aedeomyia; (2) pyriform particolored scales, half dark, half white-e.g., in Mucidus; (3) large inflated scales, as in Cyclolepidopteron; (4) in general, lanceolate or long and narrow.
These consist of three sets: (1) Border scales-small flat scales; (2) long lanceolate scales projecting from the border; (3) shorter lanceolate scales lying between No. 2.
These are for the most part flat scales-(1) In Sabethes they are hair like and occur in tufts or paddles; (2) in Mucidus, Psorophora, etc., they are elongated and project from the legs. The division of the Culicidce into subfamilies is based mainly on the length of the palpi in the male and female, together with the absence or presence of scales or hairs on certain parts. We have the following 7 subfamilies:
1. Palpi long in both sexes, as long as the proboscis in the female......Anophelina.
2. Palpi long in both sexes, nearly as long as or rather shorter than the proboscis in the female.....................................Megarhinina.
3. Palpi long in male, short in female................................Culicina.
4. Palpi long in male, short in female, postscutellum with hairs and scales. .Joblotina.
5. Seven longitudinal veins (not six)........................Heptaphlebomyina.
6. Palpi very short in female and male...........................Aedeomyina.
7. Proboscis short, not formed for piercing.........................Corethrina.
classification of culicidae.*
Palpi about as long as proboscis in male, nearly as long as proboscis or rather shorter in female. First forked cell very small-smaller than the first posterior forked cell.
Genus 1: Megarhinus: Palpi, 5 segments in male and female, proboscis bent, characterized-(1) By their large size (elephant mosquitos); (2) their brilliant metallic colors; (3) the caudal tuft of hairs on each side of the abdomen; (4) head clothed with flat scales only. Species six.
* Mr. F. V. Theobald, author of "A Monograph of the Culicidce of the World," has very kindly read through the manuscript of this systematic portion.
Genus 2: Toxorhynchites: Easily distinguished from the former by the palpi, 3 segments in 9, quite short. Species four.
Palpi short in , long in a. Anterior forked cell as long or longer than first posterior forked cell. Posterior cross vein usually nearer the base than the midcross vein, but in rare exceptions may be nearer apex (Theobaldia incidens).
Genus 1: Janthinosoma: Easily distinguished from Culex by the densely scaled hind legs, giving a characteristic appearance. Hind tarsi white. Palpi densely scaled. Head, flat, broad spindle scales, and some upright forked. A pseudo vein runs through the first basal cell.
Genus 2: Psorophora: (1) Proboscis bent in $; (2) palpi in a very long, 5 segments; (3) densely scaled long legs. Species four.
Genus 3: Mucidus: At once told by their molcly, ragged appearance. (1) Wing scales large, half dark, half white; (2) head and thoracic scales long, twisted, expanded at the apex; (3) legs densely scaled, with projecting scales. Species five.
Genus 4: Desvoidea (syn. Armigeres): Head, flat scales only, with a few upright forked. Distinguished from Stegomyia by-(1) Unbanded tarsi and abdomen; (2) palpi in a untufted, thin, and acuminate; (3) palpi in $ very pointed and clothed with bristles only. Species two.
Genus 5: Stegomyia: (1) Head, flat scales only and a few upright forked; (2) palpi, 4 segments in $, 5 in a, the segments about equal in length; (3) scutellar scales, flat. Generally black and white mosquitos, with banded legs and abdomen. Very persistent and silent in their attacks. Species twenty. S. fasciata: (1) Tarsi basally banded white; (2) proboscis unbanded; (3) thorax dark brown, a pure white, broad curved band on each side, curved inward about the middle of the mesonotum, and continued backward to the scutellum as a thinner line; two thin parallel pale lines between the curved ones; two white patches in front near the neck; (4) ungues of $ toothed. Transmits yellow fever.
Genus 6: Theobaldia: (1) Palpi in a clubbed as in the Anophelince. (2) Palpi in 5 segments, apical one mammilliform. (3) Wings densely scaled and collected into spots, thus forming a " spotted wings " genus. Species five.
Genus 7: Lutzia: Distinguished from Theobaldia by-(1) The palpi in $ have 3 segments only; apical joint is not mammilliform. (2) Palpi in & 3 segments, not clubbed. They also form a group of "spotted wings" mosquitos. Species one.
Genus 8: Culex: Distinguished from Stegomyia by the head scales, which are mainly narrow curved, with upright forked scales posteriorly and flat scales only laterally. Palpi in 3 segments, third segment as long or longer than the other two. Scutellum, narrow curved or spindle scales. C. mimeticus has spotted wings. Species very numerous.