98 THK HEl'OKT OK TIIK [ No. 10 



mixture on one side. Examination shows no injury on either lot. Here and there could 

 be seen a tree not doing well, but that was owing to the spray of a year before with pure 

 kerosene. The buds were not injured. The growers in his region never use whale-oil 

 soap, because it destroys the buds. They have used it during midwinter and it destroyed 

 buds, and have now given it up, 



Mr. Wood worth said that he did not wish his former remarks to be construed to 

 mean that there is no future for crude petroleum as an insecticide, but he desired to 

 emphasize the fajt that there is a great deal t3 learn. In some of the large orchards in 

 Oalifornia crude petroleum has been used with euccess, but not against the San Jose 

 scale. He is of the opinion that there is a great future for crude petroleum, and that the 

 time will come when it will be cheaper in the East. In California it is the cheapest 

 insecticide that can be bought. 



Three papers were read by Mr. Clarence M. Weed on " The oviposition of an egg 

 parasite of Vanessa antiopa"; "The oviposition of Cacmcia cerasivorara," and "The 

 relation of Pimpla conquisitor to Olisiocampa Americana." Ihe last named insect 

 (Pimpla) is the most important parasite which attacks the pupa of the apple tree tent- 

 caterpillar. 



Hydro CYANIC- AOiD gas. 



The reading of a paper by Prof. Fernald on " The Marguerite Fly," which he has 

 retained for publication elsewhere, led to a discussion regarding the use of hydro-cyanic 

 acid gas. 



Replying to a question from Mr. Johnson, as to whether hydro- cyanic acid gas had 

 been u(ed, Prof. Fernald stated that there was objection to the use of this substance 

 among florists, who have an exaggerated idea of the danger involved and will not often 

 nse it. He had no doubt hydro cyanic-acid gas would be more effective, but thought the 

 florists would prefer to use carbon bisulphide, as this substance had proved satisfactory. 



Dr. Fletcher thought that remedial work against the flies during the winter would 

 be better than work against the larvae after they have eaten the leaves. 



Prof. Fernald replied that the problem had been thus far looked at by him entirely 

 from the florists' standpoint, and the insect treated in the stage at which the florists 

 would first see it and want to treat it. He was certain, however, that the fly could be 

 handled by fumigating the greenhouses. 



Mr. Johnson stated that one could not be too careful in the nse of hydrocyanic-acid 

 gas, and he wanted to caution all those who used it. In one instance, after preparing 

 the chemicals necessary for generating the gas, he thought he would take his chances in 

 dropping the cyanide in the jar and get out, but he felt the eflects of the gas almost 

 immediately. By the time he reached the door a haze came over his eyes, everything 

 looked black, and a feeling similar to blind staggers overcame him. Experience has 

 proved that it is not a trifling matter, and he would caution all who had occasion to use 

 the gas. At the same time he felt that hydrocyanic acid gas was the coming material for 

 the destruction of certain insect pests in mills where stored grain and other products be- 

 come infested. He had recently performed one of the largest experiments ever under- 

 taken in the use of hydrocyanic acid gas, in a five story brick mill in Canada. Over 150 

 pounds of potassium cyanide was discharged in the mill, and the results were very gratify- 

 ing. It practically eliminated the flour moth from the mill. 



Dr. Fletcher said he did not think enough care could be taken in giving instructions 

 when recommending hydrocyanic-acid gas for general use, especially in this stage of 

 introducing it, as a fatal case or two would put an end to its use entirely. Several strik- 

 ing instances had lately been mentioned which show the intensely poisonous nature of 

 this gas. Much more care, instead of less, than has been exercised in the past is neces- 

 sary. With regard to the use of bisulphide of carbon, he certainly was not satistiod with 

 its use in mills and had not got the results promised for it. He was very sorry Mr. 

 Marlatt was not present at the meeting, as his laisser-faire policy had given him a lot 

 of trouble with the people he had to deal with, and he was of the opinion that some 

 others of the Association might have liked to discuss that matter sainewhat. 



Mr. Webster stated that his fumigating houses in Ohio are covered carefully and 

 made perfectly air tight by the use of layers of building papor, but if the ordinary 

 nurseryman makes his own fumigating house he would not make it any more air-tight 



