BEHAVIOR OF SOME SOIL INSECTS. l6/ 



hour, but never fully recovered. Graph 5 shows the reaction of 

 an Evarthrus sodalis larva, which had been outside in freezing 

 and thawing weather for eighteen days, to dry air and a tempera- 

 ture of 22.5 C. There was a tendency in this larva to avoid the 

 driest air. This is shown not so much by the time spent in the 

 dry air but by the fact that in only one instance did the larva 

 reach the end of the cage containing the dry air. It was in the 

 dry air for a greater length of time than in the other air but this 

 was due to its squirming, twisting and slower movements. Graph 

 6 shows the reaction of an Evarthrus sodalis larva, which had been 

 outside in frozen ground for five days, to dry air at a temperature 

 of 16.5 C. The larva was brought in from the outside and al- 

 lowed to revive for a few minutes before the experiment was 

 started. The larva behaved more normal than those in graphs 

 4 and 5 and showed a greater tendency to select air suitable to 

 itself. 



Graph 7 shows the reaction of an Evarthrus sodalis larva to 

 different rates of air flow at a temperature of 18 C. and a relative 

 humidity of about 44 per cent. Although the larva was affected 

 by the different gradients of evaporation thus produced, it showed 

 no tendency to select its air. The flow of air in the different 

 thirds of the cage was o, 13.3, and 69.5 liters, respectively, per 

 minute. Graph 8 shows the control of an Evarthrus sodalis 

 larva at a temperature of 23 C. at the start and 26.5 C. at the 

 end. Graphs 9, 10, and n show the reactions of three Evarthrus 

 sodalis larvae to air of practically the same temperature and 

 relative humidity in corresponding parts of the cage but with 

 different rates of air flow for each experiment. In graph 9, 

 with an air flow of 13.3 liters per minute or 3 millimeters of water 

 displaced, the larva was affected by the dry air but showed 

 little tendency to avoid it. In graph 10, with an air flow 

 of 19.0 liters per minute or 6 millimeters of water displaced, 

 the larva showed no tendency to avoid the dry air. It was, 

 however, affected, and became sluggish and less active as the 

 experiment continued. Graph n shows the reaction of an 

 Evarthrus sodalis larva to an air flow of 22.4 liters per minute or a 

 displacement of 9 millimeters of water. With this rate of air 

 flow the larva selected the wet air and was in much better con- 



