New York Agricultural Experiment Station. 347 



of humidity and temperature, only the fumigations at .3 gram per 

 cubic foot will be considered. The work as a whole is briefly sum- 

 marized as follows: 



Tests at .15 gram per cubic foot. — Thirty tests ranging in time 

 from one to sixteen hours. Of the fumigations ranging from one 

 to four hours none were effective, while some of the experiments of 

 four to ten hours' duration were effective in that all of the cater- 

 pillars were killed. The tests of sixteen hours' duration were all 

 effective. 



Tests at .2 gram per cubic foot. — Five fumigations ranging in dura- 

 tion from three to fifteen hours gave results similar to those above. 



Tests at .3 grain per cubic foot. — To be discussed fully later. 



Tests at .6 gram per cubic foot.— Twenty-five fumigations ranging 

 in duration from one to five hours. Of the fumigations lasting one 

 hour none were effective, those of one and one-fourth partially, and 

 those lasting four and five hours entirely effective. 



Tests at .75 grams per cubic foot. — Three fumigations of one hour 

 duration at temperatures of 33 to 70 degrees, all larvae killed. 



Tests at .9 gram per cubic foot. — Three fumigations of one hour 

 duration ranging from 24 to 70 degrees F., the test at 24 degrees F. 

 wholly ineffective. 



TESTS WITH .3 GRAM OF CYANIDE PER CUBIC FOOT. 



Description. — These consist of thirty-eight separate fumigations, 

 that ranged in duration from one to sixteen hours. The number of 

 individuals included in each test depended upon the number avail- 

 able at the time the test was made, at least ten larvae being used in 

 each experiment. The temperature was noted at the beginning and 

 end of each fumigation and the average of these readings was taken 

 as the temperature of the test. The condition of humidity was 

 secured by the use of a sling psychrometer. The readings were taken 

 frequently until the range of humidity surrounding each fumigator 

 was learned, and from time to time during the course of the work. 



Discussion.— By a study of the data in Table I, opposite, it will 

 be noticed that the fumigations made at low temperatures are least 

 effective as judged by the numbers surviving treatment. This 

 difference is apparent by comparing individual fumigations or by a 

 mass comparison of the data. It will be seen that, of twenty-seven 

 fumigations ranging in time from one to four hours and at tempera- 

 tures above 59 degrees F., ten were successful in that all the insects 

 were killed. Opposed to this, six fumigations ranging in time from 

 one to five hours at temperatures of 48 degrees or less were all unsuc- 

 cessful. By combining the results of comparable experiments, we 



