168 MOSQUITOES OF NORTH AMERICA 



a number of living Anopheles and Culex larvge. The bottom of the bottle was 

 literally covered with heads, breathing tubes and decaying parts of the larvae 

 which these big cannibals had destroyed on the way. There were no plants in 

 the bottle. 



" [I] observed one Psorophora attack another. It seized its victim in the thin 

 tissue which unites the breathing tube to the body. With its own breathing tube 

 at the surface, it held its victim firmly in spite of its wiggling in its struggle to 

 escape, keeping it always below the surface. Of course with its advantageous 

 hold it could quite easily keep its victim from getting a fresh supply of air and 

 thus it was drowned. I did not see that the victim made any attempt to bite its 

 captor, only wiggling violently. After several minutes it seemed to be nearly 

 dead, struggling occasionally and the valves at the end of the breathing tube 

 could be seen to frequently open and close in the water. When disturbed the 

 victor would now swim down with its prey, soon coming to the surface again 

 but never once losing its hold. 



" Another larva came up and proceeded to assist the victor, eating off all the 

 anal flaps of the victim. When disturbed again the second one let go but the 

 first one held on and was taken out in a watchglass, nearly all the water removed 

 therefrom, and examined under a compound microscope. It still held to the 

 same place, the mandibles working far into the mouth and carrying the tissues 

 with it but without appearing to masticate them. It was apparently sucking 

 the juices from the victim which was shrinking in size. 



" Another Psorophora was observed to take a 3/4 grown Culex larva by the 

 head and swallow it whole as a snake does a frog. The whole operation did not 

 take more than half a minute. 



" The mouthparts are rarely moved except when attacking prey. Yesterday I 

 saw one Psorophora seize a piece of water plant and bite enough to pull it along 

 with it. 



" I divided the Psorophora larvge into three lots of 16 each in evaporating 

 dishes and from a bucket of standing water back of insectary, I procured a large 

 number of Culex larvge which I put into the Psorophora dishes. Immediately 

 they seized upon the Culex and 8 or 10 at one time had Culex larv^ part way 

 down. In only one case out of many (probably 40-50) did I see a Culex seized 

 tail first. It took from 2 to 3 minutes to swallow the largest Culex larvge and 

 from that to perhaps 20 seconds for very small ones. 



" The method of catching is as follows : The Culex hang at the surface head 

 downward while breathing. Sometimes the Psorophora floats along in similar 

 position toward it, sometimes remains motionless till Culex comes within reach. 

 When they have reached a position so that Culex hangs almost directly over 

 the head of Psorophora, like a flash, before Culex has time to move, the Psoro- 

 phora turns its head (its mouth is on under side) and seizes Culex by the head 

 in a fatal grasp, pulling it under and, in spite of its victim's struggles, quickly 

 swallowing it whole. 



" I examined some excrement just as it came from one larva and found that 

 it was composed of the breathing tube and the two main tracheal tubes from the 

 body of the victim passed whole through the alimentary canal of the cannibal. 

 From these observations on eating whole larvae it may be inferred that practically 

 all the heads and breathing tubes which strew the bottom of my jars by hun- 

 dreds, yes thousands, have passed through the alimentary canals of the Psoro- 

 phora larvge. 



"In the case of the Psoroplwra eating each other, the strongly chitinized 

 breathing tubes and the cylinder around the last segment are rejected as too 

 tough, but in the case previously observed this day fully 1/2 the length of the 

 body posteriorly has been thoroughly chewed up and the inner soft parts ab- 



