New York Agricultural Experiment Station. 



349 



secure the data in Table II, which are so chosen that the effects 

 due to moisture are nil and the general percentages represent differ- 

 ences due mainly to temperature. 



Table II. — Comparison of Fumigations Made at Temperatures Higher than 



59° F. and Lower than 49° F. 



Cyanide used at .3 gram per cubic foot. Data Selected from Table I. 



In Table II, it should be noted that in six fumigations ranging in 

 time from one to five hours at temperatures less than 49° F., sixty- 

 six per ct. of the caterpillars survived, while of twenty-one fumiga- 

 tions ranging in time from one to four hours at temperatures above 

 59° F., only twenty-five per ct. survived. 



Even more striking are the effects of moisture, as will be seen by 

 reference to Table III. These experiments, made under tempera- 

 ture conditions that were very similar, show that only three per ct. 

 of the larvae survived when the air was moist as opposed to fifty-six 

 per ct. when the air was dry. In addition, five of the eight fumiga- 

 tions made under moist conditions were entirely successful in that 

 all of the insects were killed, while none of the eight tests made in a 

 dry atmosphere resulted in the death of all the caterpillars. 



Of most interest in this connection is the combined influence of a 

 humid atmosphere and a high temperature as compared with the 

 opposite condition. The data at hand do not afford comparable 

 experiments sufficient in number to make a comparison on this basis. 

 But by an examination of the whole table the combined effect of 

 temperature and moisture may be noticed. Of the twenty-five 

 failures recorded in Table I, that is, experiments in which some of the 

 larvse survived the treatment, five were at a temperature lower than 

 seventy, five were in a relative dry air, and six were made at both low 



