THE MOSQUITOES OF THE SOUTHEASTERN STATES 7 



There are four stages in the life cycle of a mosquito — the egg ; the 

 larva, wiggler, or wiggletail; the pupa or tumbler; and the adult 

 winged insect or imago. The eggs are matured in batches of 50 or 

 less to 200 or more, and several such batches may be laid by one 

 female. Among the bloodsucking species, a blood meal is usually 

 necessary for the production of eggs. When ovipositing, some spe- 

 cies glue the eggs together into a raft or boat-shaped mass (fig. 3, A) 

 which floats on the water, other species deposit the eggs singly on 

 the water, and still others oviposit on the soil at the edge of the water 

 or in moist depressions. The eggs of Anopheles (fig. 3, G) have 

 lateral structures that keep them afloat. The incubation period is 

 short in warm weather (usually 2 or 3 days), but in certain species, 

 particularly Aedes and Psorophora, the eggs are able to withstand 



Figure 3. — Eggs of mosquitoes: A, Egg raft of Gulex restuans; B, egg of 

 Aedes taeniorhynchus ; G, egg of Anopheles quadrimaculatus, showing floats. 

 (Howard, Dyar, and Knab.) 



long periods of drying; in fact, they appear to require a certain 

 amount of drying, and sometimes exposure to cold, before they will 

 hatch. 



The larvae of all mosquitoes are aquatic and most of them free 

 swimming. Although possessing tracheal gills, the larvae of most 

 species must come to the surface for air, and an elongated air tube 

 or other modified apparatus is provided for obtaining air through 

 the surface film. During the period of development, which lasts 

 4 to 10 or more days, the larval skin is shed four times, each suc- 

 cessive instar showing a progressive increase in size. The larvae in 

 the first two instars are very small and are easily recognized as 

 immature. In the third instar the plumose hairs have fewer branches 

 than in the fourth instar, and the immature Anopheles larvae usually 

 have a collar of dark sclerotin around the base of the head. 



