8 N. H. AGRI. EXPERIMENT STATION [Bulletin 243 



THE LARVA 



The larva is the growing stage of the mosquito. During the larval 

 period or larval stages the insect feeds a great part of the time and 

 stores up food for use during the pupal period. When first hatched the 

 larva is very small, but it generally grows quite rapidly. During its 

 growth it moults, or sheds its skin, four times. The larva is often called 

 a wriggler because of its method of swimming backward by whipping 

 the abdomen from side to side. 



The larva or wriggler is small and slender in general appearance. The 

 thorax and abdomen vary from dirty white or yellow to light gray or 

 pale brown in color. The head, air-tube and part of the ninth abdom- 

 inal segment are light brown or brown, and the head often has definite 

 markings. The head is distinct and has a pair of black eyes, a pair of 

 short antennae toward the front of the head, and two thick tufts of hair 

 on the front of the head called the mouth brushes. The thorax is com- 

 pact, broad and somewhat flattened. The abdomen is slender and elon- 

 gate, consisting of nine cylindrical segments. On the dorsum, or top, of 

 the eighth segment is a tube used for breathing, called the air-tube. The 

 air-tube varies in length, being long and slender in some species, shorter 

 in others, and very short and stout in Anopheles. The larvae of most 

 species have a row of stout, tooth-like spines along each side of the air- 

 tube called the pecten. On each side of the eighth segment is a group 

 of large spines called the lateral comb. In Anopheles each comb is re- 

 placed by a single, large, toothed plate called the lateral plate. Project- 

 ing from the tip of the ninth abdominal segment are four fragile, leaf- 

 like appendages, the anal gills. Near the gills is a thick tuft of long 

 hairs. Single hairs or tufts of hairs are scattered over the larva. 



The larvae of all mosquitoes breed in standing water. A few species^ 

 are known to breed also in the slow-flowing, vegetation-choked back- 

 waters of streams, but we have never found larvae in these places in 

 New Hampshire. The breeding places of mosquitoes vary considerably 

 and are dependent on the location chosen bj' the female for egg-laying. 

 Some mosquitoes prefer open, sunny pools, some shady pools in wooded 

 regions. Some are never found far from the salt-marshes of the sea- 

 coast, while others have veiy specialized breeding places. Clean water 

 is required by some species, many can use dirty water, while a few ac- 

 tually prefer foul water for breeding. Permanent or semi-permanent 

 bodies of water, as swamps, the vegetation-choked borders of lakes, 

 springs, and bog pools, are preferred by some species, but the majority 

 of New Hampshire mosquitoes breed in temporary collections of water 

 formed by melting snow, heavy rains, or floods. The salt-marsh mos- 

 quitoes breed only in the pools on the salt marshes filled by high tides 

 or heavy rains. A few species are more or less domesticated, breeding 

 primarily about houses in collections of water in rain-barrels, empty 

 cans, bottles, etc. The pitcher-plant, rock-pool, and tree-hole mosqui- 

 toes breed only in these specialized locations, from which they take their 

 names. The preferred breeding place of each mosquito is given in the 



