42 



Mr. Kirkland described these experiments, which were quite varied 

 and included the poisoning of portions of leaves or of one or both sur- 

 faces, and also tests with larvae of different ages. The result of the 

 whole series would seem to indicate that the presence of the poison was 

 not noticed by larvae and had little if any effect in deterring them from 

 feeding. 



Considerable discussion followed, various members supporting both 

 sides of the question. 



Mr. Smith stated that his experience was confirmatory of Mr. Marlatt's, 

 and he had noticed the same repugnance in the case of the elm leaf-beetle. 

 He was quite inclined to agree with Mr. Marlatt that this repugnance, 

 due to the presence of poison, is the explanation of the slow action of 

 arsenicals, which is of rather common experience. 



Mr. Fern aid explained that the experiments under his direction had 

 been with the larvae of the gypsy moth, which in this and other ways 

 manifest characteristics and powers of resistance widely different from 

 other larvae. 



Mr. Johnson described an experience which he had had with the 

 apple leaf-skeletonizer, attended with similar manifestation of repug- 

 nance of the larvae to poisoned leaves. He described feeding experi- 

 ments in cages in which 100 larvae were included in each cage and 

 fed with leaves poisoned at a definite strength. In one instance the 

 larvae refused to feed for three days. 



Mr. Webster, referring to the statement concerning the use of oily 

 Avashes on trees by Mr. Marlatt, described an experience with the use 

 of pure kerosene on peach trees for the San Jose scale in Ohio. The 

 trees had been cut back rather severely and were in December sprayed 

 thoroughly on trunk and branches with pure kerosene. Upon exami- 

 nation in March these trees were in thrifty condition and presented no 

 injury from the application. He was so pleased with the results that 

 he purposes to recommend the use of pure oil, and stated that many 

 orchards would probably be sprayed with this substance the ensuing 

 winter. He further called attention to the fact that the Bordeaux 

 mixture sprayed on plants often afforded protection by rendering the 

 foliage distasteful in much the same manner as an arsenical. He 

 instanced particularly the benefits of Bordeaux as a means of protect- 

 ing potato vines from the attacks of Diabrotica vittata. He referred 

 also to the fact that no general deductions can be made from the habits 

 or behavior of any particular insects with poisons, and that with differ- 

 ent species vastly different results are to be expected. He referred to 

 his experience with the grapevine Fidia, which he had kept in a breed- 

 ing cage through which a living grapevine was passed which had been 

 poisoned with arsenicals at the rate of 4 ounces to 50 gallons. The 

 beetles lived for several days on this poisoned food. He referred also 

 to the fact that the different results obtained with the same insect are 

 not always due to faulty material, but rather to the men who make the 



