52 



ENTOMOLOGY FOR MEDICAL OFFICERS 



natural or artificial, temporary or permanent, or even in 

 pools of sea-water ; but they are not found in any parts of 

 streams or rivers where the current is rapid. They are 

 extremely active, and though their food usually consists of 

 algse and such vegetable matter, there are some species that 

 are carnivorous and predatory. 



The three regions of the body in the Culicid larva are all 

 well defined. 



The head (Figs. 14, 15) is a rounded chitinous capsule with 

 well-developed appendages, and all its parts show specific 

 differences. The eyes in the young larva are rather irregular 

 masses of pigment, but in older larvae they become indistinctly 

 faceted. The antennze are, for a larva, long. The clypeus 



month-br 



mouTh-njffs 

 rakes '- 



anlenna- 

 maxilla 



Fia. 14.— Head of a non-rapacious Tjarva. 



FiQ. 16.— Head of a rapacious Larva. 



is prominent, and on either side of it are attached large tufts 

 of hairs ; these, which are known as " mouth-brushes," have 

 a rotatory motion and are used for sweeping food into the 

 mouth. In predatory larvae the brushes may be replaced by 

 combs, or rakes, of stout chitinous prehensile bristles or hooks 

 (Fig. 15). The mandibles are strongly chitinised, sharply 

 serrated, and usually dark coloured. The maxillae are 

 bilobed plates fringed with hairs, the outer lobe sometimes 

 being elongate. The labium is represented by a dark 

 coloured, triangular, chitinous plate, the edge of which is 

 more or less serrated. On the front of the head, between the 

 antennae, hairs of various forms, but of definite arrangement, 

 are often found. 



The thorax is a broad mass which shows its composition 

 of 3 segments only in the serial arrangement of its hairs • 



