MOSQUITO BIOLOGY 87 



were sent to the laboratory. With this information I went down to 

 Trenton on September 27, and with a small net fished the bottom mate- 

 rial, where I had previously found eggs. When the water had finally 

 trickled through the cloth, a mass of brown silt was left and in this were 

 two well grown larvae. Others were taken in the same way, but it was 

 not until the bases of the tussocks were swept that larvae were really 

 gotten in some numbers. Collecting was slow, on account of the fact that 

 each sweep of the net would bring with it a mass of partly decomposed 

 vegetable matter and the fine silt would clog the meshes of the cheese 

 cloth net. In all, forty-seven wrigglers were taken in two hours, and 

 they ranged in size from those apparently just out of the egg to those 

 one-fourth of an inch long, and representing stages from one to four. 

 The great majority were of the largest size. No larvae were taken at a 

 depth less than six inches from the surface, and most all at a depth of 

 ten inches and over. Specimens could be gotten as far down as the net 

 could be forced through the matted vegetable roots. Mr. Brakeley, con- 

 tinuing his washings, sent in six larvae on September 26, four on Octo- 

 ber 1, four more on October 3, and eleven others on October 11. Most 

 of these were small, only three being in the third stage. Collections at 

 Trenton turned up eighty larvae on October 1, 109 on October 3, 

 forty-two on October 9, and forty as late as November 1. 



HABITS OF THE LARVA 



As before noted, the larva is not dependent upon the outer air for its 

 existence, and, after once leaving the surface from the egg, probably 

 never returns to it until it has assumed the pupal stage and is ready to 

 emerge as an adult for flight in the open air. Unlike the larvae of cer- 

 tain other mosquitoes in New Jersey, which rarely come to the surface, 

 the anal gills are not unusually developed, though they are provided 

 with obvious trachea. It seems that in this case the wrigglers are able to 

 obtain a supply of oxygen through the open cellular tissue of the roots 

 of certain grasses, which they pierce with the curiously shaped air tube 

 that is especially adapted for this purpose. They do not permanently 

 anchor themselves to one spot on the root, but can very readily detach 

 the tube and move to some other place. At the laboratory over 100 lar- 

 vae were put in a two-gallon jar into which was placed a portion of a 

 tussock around which the larvae were collected in the swamp. In a short 

 time most of them had disappeared within the sod, though a number 

 worked their way through and came out in the crevices on the other side 

 where the sod rested against the glass, giving a splendid opportunity 

 for study. Here they were seen to attach themselves to the grass roots 



