18 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



AFTERNOON SESSION, FRIDAY, DECEMBER 28, 1906. 



The meeting was opened with a discussion of the presidential 

 address and of the paper presented by Mr. Washburn. In reply to an 

 inquiry concerning the effect of fumigation on insects attacking grain, 

 Mr. Kirkland stated that he had used hydrocyanic acid gas in fumi- 

 gating a mill, and had secured excellent results. One hundred and 

 twent}^-nve pounds of cyanide were used, and as the building was not 

 very tight this was applied at the rate of 1 ounce of cyanide to 80 

 cubic feet of space, and the building was kept closed for six hours. 



A discussion then followed on the use of arsenate of lead. Mr. 

 Frost stated that shade trees of average size could be sprayed with 

 this poison for from 40 to GO cents each, and that in woodland areas 

 the price could be reduced to from 25 to 40 cents per tree. Such 

 treatment is applied in regions infested with the gipsy moth, and 

 thousands of trees are being sprayed with this poison. In reply to a 

 question by Mr. Slingerland he stated that arsenate of lead does not 

 burn the foliage to any appreciable extent if it is properly prepared. 

 Men in his employ used 14 tons of this poison during the past summer, 

 and in such large lots it was secured at from 11 to 12 cents per pound. 

 He did not consider it advisable to attempt its manufacture when 

 good material could be bought at this price. 



Mr. Britton remarked that his experience in Connecticut had led 

 him to believe that peach and Japanese plum trees could not be 

 sprayed while in foliage without causing injury. 



Mr. Kirkland stated that in manufacturing arsenate of lead it was 

 necessary to form the precipitate in large vats, and if made in this way 

 there would be very slight chance of foliage injury. In some cases, 

 however, delicate leaves might be burned. 



Mr. Marlatt inquired if the yellow acetate of lead was as good as the 

 white acetate for making arsenate of lead, and Mr. Kirkland replied 

 that the arsenate of soda which is imported carries about TO per cent 

 As 2 5 and could be bought at New York, duty paid, for about 8 

 cents per pound. This year white arsenic is selling for 8 to cents a 

 pound. The 50 per cent grade of arsenate of soda is made by fusing 

 Avhite arsenic and soda together. Acetate of lead is sold in different 

 grades — known as crystallized, white granulated, brown, and dark 

 brown. The best manufacturers of arsenate of lead use white gran- 

 ulated acetate of lead. 



Mr. Burgess stated that he had observed considerable injury from 

 using homemade arsenate of lead, and in several cases this proved to 

 be due to the fact that the arsenate of soda had been adulterated with 

 salt. In one case an analysis showed that the sample contained over 

 25 per cent of salt. 



