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The MOSQUITO 



HERBERT M. HALE, South Australian Museum 



In the last number of Aquatic Life the 

 larva and pupa of the mosquito were 

 described; the present article deals with 

 the adult insect. 



The active little pupa contains the de- 

 veloping imago or perfect insect, the 

 head and thorax being enclosed in the 

 larger part, whilst the curved tail is the 

 abdomen. In a short time the mosquito 

 is ready to leave the chrysalis case, and 

 commence the final period of its life his- 

 tory; the photographs show the manner 

 in which this change is effected. The 

 mosquito illustrated is Culex fatigans, a 

 widely distributed species, pictures of the 

 immature stages of which appeared in 

 the previous paper. 



When fully developed the pupa is very 

 dark in color; if disturbed it is reluctant 

 to dive. By now placing it in a small 

 aquarium the completion of the meta- 

 morphosis may be admirably observed. 



Just prior to emergence the pupa un- 

 bends its abdomen and floats at the sur- 

 face in a horizontal position. The en- 

 closed mosquito pushes upwards against 

 the skin, which slowly bulges until the 

 portion between the breathing-tubes pro- 

 trudes above the surface. This is then 

 burst open and the thorax immediately 

 appears through the slit — emerging first 

 because the head is bent downwards be- 

 neath it in the chrysalis. The insect rises 

 up out of the case with a very steady and 

 regular motion, and excepting for an oc- 

 casional wriggle of the abdomen, without 

 visible effort. In the third picture the 

 antennae are released, and it is apparent 

 from the feathery appearance of these 



organs that the emerging mosquito is a 

 male. The body is now almost upright 

 and is supported by the floating pupal 

 skin ; the legs are held stiffly along the 

 sides and are still partially enclosed. The 

 slightest breeze will cause the mosquito 

 to career over the surface as if in a min- 

 iature boat, and a sudden gust may 

 upset it. Even when capsized the with- 

 drawal is frequently completed, but the 

 insect is entangled in the surface film 

 from which it cannot extricate itself. 

 Individuals which have thus perished will 

 often be seen on the surface of a pond. 

 If fishes or predaceous aquatic insects 

 are present there is the additional danger 

 of an attack from below. 



The wings are extracted before the 

 legs are entirely withdrawn from their 

 sheaths. The front pair is freed first 

 and greater stability is attained by rest- 

 ing them on the surface film, the latter 

 being indented but not pierced by the 

 infinitesimal pressure of these delicate 

 members. The middle pair soon follows 

 and finally the ends of the long hind 

 legs are drawn out. 



Our mosquito is now free and after 

 resting until the wings are- dry, would 

 in the usual course of events, flutter 

 away in search of a mate. Being im- 

 prisoned in a glass cell, however, it set- 

 tles on the side of this and we may 

 examine it at leisure. The head is much 

 smaller proportionately than in the larva, 

 in which the eyes were represented by 

 mere blotches of pigment, whereas each 

 now consists of a great number of 

 lenses. Tiny, variously colored scales 



