192 AGRICULTURAL EXPERIMENT STATION. 



These pools do not really differ from dozens of others in the 

 city, and even in the vicinity, where the species does not occur. 

 One of them becomes very foul occasionally from a sewage ad- 

 mixture and this seemed in no wise to discompose the insects. 

 The others have the ordinary shale mud bottom with little or no 

 vegetation. The larvae somewhat resemble those of Psorophora 

 at first sight and, as they always occurred with pipiens, it was 

 believed that they might be predatory; but a series of experi- 

 ments failed to bear out this belief. 



Prof. Glenn W. Herrick, of Mississippi, described this larva in 

 1904 and detailed some of its habits, which it may be interestng 

 to quote : "I first noted the larva in an open sewage drain of the 

 college campus in 1901. They attracted my attention by their 

 large size as compared with the larvae of C. fatigans, which were 

 so numerous in the same drain. At this time several adults were 

 taken from the weeds and grasses overhanging the ditch. * * * 

 In the summer of 1903 I noted scores of large larvae in a road- 

 side pool near Starkville, Miss. At first sight they appeared to 

 be the larvae of Anopheles, for apparently they were in horizontal 

 positions. Never having seen Anopheles larvae so abundant, it 

 seemed worth while to stop and examine them in some detail. 

 Much to my astonishment these larvae were found to be mem- 

 bers of the genus Culex, or at least of some genus closely related 

 to Culex. Moreover, the great majority of them were lying 

 apparently horizontal, just below the surface film of water. 

 * * * From this time forth many larvae of this species were 

 found in other rain-water pools and abundant opportunity was 

 afforded to observe them. With the one exception of those found 

 in the sewage ditch, I have always found these larvae in transient 

 rain-water pools. 



" The larvae are interesting from the position they assume in 

 the water. When the larva rises to the surface it assumes at 

 first about the same position as the larva of Ciilex. But after 

 a moment, if left undisturbed, the body, with a slight jerk, floats 

 quickly to an approximately horizontal position with the head on 

 a level with the surface of the water, in which position the mouth 

 brushes are able to skim the surface, as it were. The larva can 

 change quickly and easily from the horizontal to the suspended 

 position. 'The body, instead of lying so nearly horizontal as 

 does that of Anopheles, hangs suspended — like a piece of slack 

 rope — between the head and respiratory tube and considerably 

 below the surface of the water. The respiratory tube projects 

 out of the water at least a third of its length and points forward 

 when the larva assumes the horizontal position. * * * The 



