THK EARLY STAGES OF CERTAIN WEST AFRICAN MOSQUITOS. L37 



Breeding place.— The larvae of this species were found in rot-holes in trees and 

 were associated with larvae of Culiciomyia nebulosa, Stegomyiafasciata, S. metaUica, 



S. unilineata, and S. luteocephala. 



Stegomyia unilineata, Theo. 



The head is small, though well chitinised. The antenna is short, and there is no 

 hair-tuft, a single or bifid hair being, however, visible at about half the length of 

 the shaft. In one of the specimens examined a distinct constriction occurred in 

 the antennae at a fourth of the length from their bases. Several tufts of stout hairs 

 may be seen on the head. The mental plate carries a substantial median tooth with 

 ten more slender teeth on each side, the lateral teeth becoming broader and more 

 widely separated towards the base of the plate. The brushes are small. 



The thoracic plumes are short and are formed of hairs which are subplumose at 

 their bases. The hook-like spines visible at the bases of the ventral plumes on the 

 thorax of some other members of this genus are scarcely perceptible. 



Numerous hair-tufts are present on all the abdominal segments, these are not 

 true stellate hairs, but resemble the hair-tufts on the abdominal segments of 

 S. luteocephala. A few of the constituent hairs are pubescent, the majority are 

 simple. The hairs forming the subsiphonal, siphonal and anal plumes show slight 

 pubescence. The comb consists of about eight spines with fringed bases set in a 

 single row. The siphon is about twice as long as the diameter of its base, and there 

 are 8-12 barbed spines in its pecten ; distal to the pecten is a tuft of four or five 

 simple hairs, situated a little beyond the middle of the siphon. The anal segment 

 carries a scanty beard ; the hairs on the end of the dorsum are three above and 

 one below on each side, and there is a tuft of five stout hairs — which are simple — 

 on the lateral aspect of the segment. The papillae are long and blunt-ended. 



This larva may be distinguished from other larvae of the same genus which have 

 numerous hair-tufts on the abdominal segments by the absence of hook-like spines 

 on the thorax. 



Breeding place. — The larvae were found in association with the larvae of 

 S. luteocephala, S. metallica and S. simpsoni in a rot-hole holding a small quantity 

 of water in the trunk of a Flamboyant tree (Poinciana regia) in the laboratory 

 compound at Accra (Plate IV, fig. 2). 



Mansonioides africanus, Theo. (Plate I, figs. 1, 3; text-fig. 1). 



The larva of Mansonioides africanus has already been described by Ingram (Bull. 

 Ent. Res. iii, p. 76), and has also been figured by Edwards (Bull. Ent. Res. iii, 

 p. 377). The siphon tube is complex and would appear to resemble that of Man- 

 sonia titillans, a South American mosquito, the larva of which also attaches itself 

 to the roots of Pistia. A general description of this tube has already been published, 

 but a more detailed account of the structure, especially that of the apical third, may 

 be of interest as indicating the high degree of specialisation of the breathing 

 apparatus of the larva of this species. 



The apical third of the siphon tube is more highly chitinised than the basal two- 

 thirds and appears to be movable on the latter portion. It is an incomplete tube 

 composed of two lateral chitinous lamellae with a ventral membrane connecting 

 (C394) b 



