The Pupa and the Imago 



only by violent exertions with their tails. As soon as these move- 

 ments of the tail cease, the buoyant pupa floats up to the surface 

 again. Like the larvae, they breathe air through protruding spiracles ; 

 but these air tubes, instead of being at the tail end, as in the larva, 

 are placed on the dorsum of the thorax, as two trumpet-shaped 

 structures, projecting like horns. (PL II, figs. 3, 4. ) 



The length and shape of these spiracles enable " anopheles " 

 pupae to be distinguished from those of " culex." 



" Anopheles " pupae have short, stumpy, funnel-shaped spiracles 

 (PI. II, fig. 4), while those of " culex " are longer, more slender, and 

 trumpet-shaped (PI. II, fig. 3). 



THE ADULT MOSQUITO OR IMAGO 



The adult mosquito is divided into three regions: (ij the 

 head, ( 2) the thorax, (3) the abdomen. To the head are attached 

 sensory and suctorial appendages ; while to the thorax are attached 

 the legs and wings. (See Descriptive Diagram of a female anopheles. 

 Coloured plate No. I. ) 



The head is rounded and attached to the thorax by a narrow 

 neck The portion of the head near the neck is called the nape. 

 Above and in front of the nape is the occiput. In front of the 

 occiput, and occupying the greater part of the antero- lateral portion 

 of the head, are the two compound eyes. Immediately anterior to 

 the eyes, on either side, arise the antennae, which are long, jointed 

 structures covered with hairs. In the male the antennae are very 

 prominent hairy organs (PL III, figs. 1,3); in the female they are 

 less conspicuous and almost devoid of hairs. (PL III, figs. 2, 4). 



In front of the antennas will be noted a firm median chitinous 

 prolongation, the " clypeus." Beneath the clypeus arise the mouth 

 parts, which consist of seven pieces collectively termed the proboscis. 



The mouth parts are : 



{ 1 ) the upper lip, made up of labrum and epipharynx ; 

 (2) & (3) two mandibles ; 

 (4) & (5) two maxillae ; 



(6) the hypopharynx or tongue ; 



(7) the lower lip or labium. 



The labium is a grooved structure, within which the other six 

 mouth parts are enclosed. 



[13 



