Fig. 398.—Neuration of Wing. Explanation of Wing, Veins and Cells.—A, costal cell; B, sub-costal cell; C, marginal cell; D, first sub-marginal cell (= first fork cell); E, second sub-marginal cell; F, first posterior cell; G, second posterior cell (= second fork cell); H, first basal cell; I, second basal cell; J, third posterior cell; K, anal cell; L, auxiliary cell; M, spurious cell; c, costal vein; 1st—6th, first to sixth longitudinal veins; a, a′ and a′′, incrassations (a′ called by Austen the sixth vein, a′′ the eighth vein); y, supernumerary cross vein; z, mid cross vein; p, posterior cross vein; s.c., sub-costal. (Theobald.)
Scales.—The most important structural peculiarities in Culicidæ are the scales, which form the chief and most readily observed characters for separating genera and species. The importance of scale structure has been recently ignored by some workers, who are probably right academically, but as a means of separating groups, and so more easily running down a species, the practical man is strongly advised to follow this method. As to what a genus is, is purely a matter of personal opinion. If one examines any recent standard work on entomology one will find a species being placed in varied genera by the varied authorities.
The head, thorax, abdomen and wings are in nearly all cases clothed with squamæ of varied form, of which the following are the main types (fig. 397):—
(1) Flat, spade-shaped scales (a).
(2) Narrow curved scales (e).
(3) Hair-like curved scales (d).
(4) Spindle-shaped scales (f).
(5) Small spindle-shaped scales (g).
(6) Upright forked scales (h) and (i).
(7) Twisted upright scales (j).
(8) Inflated or pyriform scales (k).
(9) Mansonia scales (b).
(10) Small broad asymmetrical scales (c).
Various other varieties are found on the wings, such as:—
(1) Narrow linear lateral scales.
(2) Narrow lanceolate scales.
(3) Broad lanceolate scales.
(4) Elongated, broad, truncated scales (= Pseudotæniorhynchus-like scales).
(5) Pyriform scales.
(6) Asymmetrical broad or Tæniorhynchus scales.
(7) Flat spade-like scales.[389]
The wings have a series of scales along the middle line of the veins, and also lateral scales to all or nearly all the veins. The wing is also fringed by a series of scales (fig. [396]), which, however, are of little systematic importance; the so-called “border scales” (b.s.) vary, however, to some extent, and are useful characters in separating some of the Tæniorhynchus.
The Classification of Culicidæ.