60 ENTOMOLOGY FOR MEDICAL OFFICERS 



The larva of Corethra (Fig. 17) is of interest, as, living in 

 the same kind of water as the larvae of other Culicidae, it is 

 predatory. It is of such extreme transparency that it is 

 known as the " phantom larva," and in repose it rests hori- 

 zontally near the surface. The head is produced anteriorly 

 into a kind of snout, at the end of which are the antennae ; 

 these are bent towards the mouth and, ending in a tuft of 

 long bristles, are prehensile. The mouth is remarkable for 

 the talon-like mandibles. The long tapering abdomen ends 

 in four tracheal-gills, and on the ventral surface of its terminal 

 (9th) segment there is a sort of vertical fin, which consists of 

 a row of many long, finely feathered bristles. There is no 

 breathing-tube nor any breathing-opening, the tracheal 

 system being completely closed. Connected with the tracheal 



Fig. 17.— Anterior and posterior ends of Larva of Corethra. 



system there are, on the dorsal surface of the body two pairs 

 of oval, pigmented dilatations or floats ; the front pair, which 

 are the larger, are situated side by side, near the middle of 

 the thorax, and probably are homologous with the breathing- 

 trumpets of Culicid pupae ; the smaller, posterior pair are 

 placed on the 7th abdominal segment. The pupa is remark- 

 able for the great size of the tail-fins at the posterior end 

 of the abdomen, and for the pointed shape and extremely 

 narrow opening of the breathing-trumpets of the thorax. 



The larva of Mochlonyx (Fig. 18) also is predatory; it 

 and its pupa are considered by Miall to be "structurally as 

 exactly intermediate between Corethra and CulexAs can well be 

 imagined "—an opinion which cannot reasonably be disputed, 

 though to the naked eye the larva looks exactly like Culex. 

 The larval Mochlonyx which, for convenience, is represented in 

 Fig. 18 in an unnatural position, the head being viewed from 



