8 MISC. PUBLICATION 336, U. S. DEPT. OF AGRICULTURE 
Aedes have shown a marked reduction in numbers within 2 weeks. 
The southern house mosquito probably lives longer than this, and the 
yellow-fever mosquito may live, on an average, a month or more, with 
a maximum of several months. 
In the North the females of Culex, Anopheles, and some other mos- 
quitoes hibernate. True hibernation of Anopheles apparently does 
not occur in the South, as the females become active during warm 
periods and larvae are found in the breeding places (J, 8, 26, 64, 147). 
The same is true of some of the culicines in the warmer sections (47, 
73). Aedes and Psorophora pass the winter in the egg stage, although 
some winter development of A. sollicttans occurs along the south At- 
lantic and Gulf coasts (66). 
The piercing organs of the female mosquito consist of six elongated 
parts enclosed in a flexible sheath called the labium. When the mouth 
parts are inserted in the skin for bloodsucking, the sheath is bent back- 
ward in the middle like a bow. There are two pairs of slender cutting 
organs, the mandibles and the max- 
illae, and two additional organs 
called the hypopharnyx and the 
labrum-epipharnyx. The latter is 
channeled, and the last two organs, 
when pressed together, form a tube 
through which blood and _ other 
liquids are drawn. A very small 
separate duct is found in a ventral 
thickening of the hypopharnyx, 
through which is injected the secre- 
tion from the salivary glands. This 
salivary secretion is responsible 
Ricune 4= “Puna ot Onler areione for the itching sensation caused 
(Howard, Dyar, and Krab.) by mosquito bites. Not all species 
of mosquitoes have bloodsucking 
females. In the genus Megarhinus the proboscis of the female is not 
adapted to piercing, and some of the species in other genera are not 
known to take blood meals. 
The mouth parts of the male are not adapted for piercing, and the 
males probably subsist on the nectar of flowers and fruit juices. Both 
the males and the females can be kept alive in the laboratory for con- 
siderable periods on fruit juices or sirups. | 
COLLECTION AND PRESERVATION OF MATERIAL 
Anopheles larvae are usually found at the surface of the water 
among aquatic vegetation or floating debris and are collected by skim- 
ming through such material with a dipper or pan. A white-enameled 
dipper, having the handle lengthened by the insertion of a cane or 
smooth stick, makes a convenient implement for collecting larvae. 
Around emergent vegetation or logs the larvae may be drawn into 
the dipper by submerging one edge so that the water flows in rapidly 
as the dipper nears the obstruction. The larvae may be removed from 
the dipper to the collecting jar with a large-mouthed pipette provided 
with a rubber nipple (fig. 5), or a spoon may be used for this purpose. 
Wide-mouthed bottles (2 to 6 ounces) make convenient collecting jars. 
