SIGNIFICANCE OF STEGOMYIA FASCIATA IN WEST AFRICA. 243 



VI. Characteristics of the Egg and Adult Larva of 



StEGOMYIA FASCIATA. 



The Eijii. — This is very elongate, blackish in colour and rather sparsely 

 studded with minute hemispherical bodies o£ whitish secretionary matter. 



The Larva.— -One o£ the marked habits of the larva is that it occasionally 

 swims and wriggles along the surface o£ the water like the larvtje o£ certain 

 Anophelines It has been shown (see p. 246) that it is capable of remaining 



Larva of Stegomyia fasciata. 



submerged for relatively longer periods than is commonly the case among the 

 larvae of numerous other Culicines. 



The siphon is about one fourth of the entire length of the abdomen and 

 about two and one half times longer than the width at the base. This 

 character is, however, not altogether reliable, as the larvae of other Culicines 

 possess siphon tubes of similar dimensions. 



The distinguishing morphological characters, which can only be determined 

 by the aid of the microscope, are as follows : — 



Antenna? smooth, the tuft being represented by a single short hair ; at the 

 apex there is a niinute but distinct second joint and a few very delicate hairs 

 (figs. 1 and 2, p. 244). The labial plate possesses 11-12 teeth on each side 

 and a larger median one ; the base is also symmetrically crenulated as shown 

 (fig. 3). The thorax is rather hairy, some of the hairs arising from four 

 distinct chitinous hooks (fig. 4), situated two on each side of the thorax. On 

 the 8tli segment of the abdomen are the lateral combs, each of these is 

 composed of from ^-10 serrated spines varying in form and also in the 



