IQOl] ENTOMOLOGICAL NEWS. 155 



and frequently rooting into it: varying the process by working along the 

 glass of the jar on the side away from the light. It was very rare that 

 an individual was observed at the surface with the spiracle in breathing 

 position. I watched patiently several times 15 minutes at a time without 

 noting a single individual rising to the top. Mr. Dickerson, one of the 

 students, watched more or less continuously for two hours on one day 

 and declared positively that during that period only a small percentage of 

 the entire number came to the top. On two or three occasions, where my 

 work was such as to allow it, I kept ajar within sight the entire day, and 

 I have no hesitation in saying that some individuals remained below the 

 surface for hours. 



Occasionally a number of specimens would be at the surface, feeding, 

 head up, so that the mouth brushes skimmed the surface, and these were 

 watched on occasions for fully 20 minutes without noting any attempt to 

 assume the breathing position. In fact, during the two months that these 

 larvae were under daily observation, the rising to the surface to breathe 

 was the rare exception rather than the rule. 



As to feeding positions, all of those figured by Dr. Howard were noted. 

 Usually they were head down over the bottom sediment or head up, feed- 

 ing along the sides of the glass or at the top. The mouth brushes serve 

 as organs of locomotion as well as for feeding, and the insects are per- 

 fectly able to make their way from place to place without moving any 

 other part of the body. 



The jerky, wriggling motion is used when they wish to get away 

 quickly, and as often to get down to the bottom as to get up to the sur- 

 face. They can and often do sink slowly to the bottom without any mo- 

 tion whatever, and often to sink more rapidly, they curl themselves up 

 into a ring. Occasionally a specimen will get hold of a bubble of gas 

 forming at the bottom and will allow itself to be floated to the surface. It 

 is immensely interesting to watch these little creatures ; but as week after 

 week went by without change, it became just a little tedious. To hasten 

 matters a little, on March ist I placed the two jars first received on a 

 water bath which was kept at a temperature as nearly constant as the 

 varying gas pressure allowed. Ordinarily the thermometer ranged be- 

 tween 100 and 110, but it has gotten as high as 120 and as low as 90. 

 These were exceptions, however, and not exceeding the ordinary out-door 

 range in June. The temperature of the water in the jars ranged between 

 80 and 90 almost uniformly. 



A difference in the rate of growth was observable after a few days, and 

 several specimens seemed approaching the adult condition ; finally, 

 March iSth, I noted the first pupa, 17 days after placing the jar on the 

 water bath. From this the adult emerged March 2ist and proved to be a 

 female C. pungens. Three other pupae were formed within a week after 

 the first, and a second adult, also a female, was obtained March 24th. 



As to the habits of the larvae in the two jars artificially forced, there was 

 little to note as different from those in the normal laboratory temperature 



