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HOW TO COLLECT 
temporary pools of rain-water; also in sluggish rivers and in salt water. 
Species that frequent houses breed in butts or tubs of rain-water or 
in other vessels of water within or in the precincts of the houses 
themselves, or in cesspools and wells which are open to the air. In 
the case of the best-known species of Culex that infest houses, the 
eggs are laid on the surface of the water in the so-called " boat- 
shaped" masses; Anopheles eggs, on the other hand, are laid 
separately, and float together into roughly star-shaped groups or in 
lines; in Panoplites and Stegomyia they are also often laid separately. 
The eggs of the different genera vary much in form. 
The mosquito larva is usually a small greenish, greenish-brown, or 
brown creature, occasionally red and blue, with a round head, a 
rounded swollen thorax, and an elongated jointed abdomen, from 
near the end of which, in Culex, JEdes, Megarhina, Stegomyia, Pan- 
oplites, and Mucidus, the breathing-tube arises. In the pupa the 
head and thorax are fused into a mass, on the sides and front of which 
depend the rudiments of the wings, legs, and proboscis, while from 
the dorsal side project a pair of funnel-shaped breathing-organs ; the 
terminal segment of the abdomen bears a pair of swimming-plates. 
In the case of Culex the larvae and pupse are exceedingly active, 
moving about in the water by a jerking or wriggling motion of the 
body ; they are under the necessity of coming to the surface to 
breathe at frequent intervals. The larva of Anopheles is more 
sluggish, and its habit is to float horizontally at the surface of the 
water, and is devoid of a prominent air- tube. 
In the case of Culex fatigans, Wied., it was found by Howard 
that the minimum time occupied by the whole life-history cycle 
was ten days — " namely, sixteen to twenty-four hours for the 
egg, seven days for the larva, and two days for the pupa." 
But the period necessary for a generation " is almost infinitely 
enlarged if the weather be cool," so that it is also permissible to 
suppose that it is accelerated by heat. 
In the perfect state the male insects die quickly in confinement, 
but the females are longer-lived. Dr. Bancroft has kept Culex tigripes 
alive for seventy days in confinement. In cold climates large num- 
bers of the perfect insects pass the winter in a state of hibernation, 
but a few as larvae [Anopheles bifurcatus). 
