41 



Mr. Wood worth mentioned that he had observed in Arkansas three epidemics 

 amongst insects which were so severe as apparently to exterminate the infested 

 species : one of these was the tomato worm. 



Mr. Fletcher asked whether Phytonomus nigrirostris had been observed as 

 injurious to clover. He had frequently found the larvae feeding on the heads of 

 clover as well as the characteristic cocoons. He had found it in many parts of 

 Canada, but upon one occasion, as recorded in his report for 1884, it was 

 injuriously abundant at Dalhousie in New Brunswick. Mr. Gillette also spoke on 

 insects injurious to clover. 



Prof. Smith gave an account of some experiments with preservative fluids. 

 He had found a mixture of equal parts of acetic acid and alcohol very satisfactory 

 both in regard to preserving form and colour of delicate insects. 



The subject was earnestly discussed by all present as being a subject of much 

 importance. Mr. Woodworth gave as a method which he had found satisfactory 

 for larvae, to kill in water heated to 90° centigrade : leave from 1 to 5 minutes ; 

 then put in alcohol 35° 1 to 2 hours, 50° from 6 to 8 hours, 75° for 24 hours or 

 more and then to absolute alcohol. This would usually preserve perfectly and 

 was a recognized process for hardening and preserving for histological purposes. 



Mr. Fletcher asked whether in the case of large larvae it was necessary to 

 puncture the epidermis so as to allow the preservative fluid to penetrate. 



Mr. Woodworth answered that this was not often necessary. 



Mr. Fletcher spoke of a large series of the larvae of Sphinx chersis which he 

 had taken during the past summer upon various species of Fraximis. They varied 

 so remarkably in colour that he was able to separate about 40 which showed 

 different markings from the usual glaucous green to a rich vinous purple with 

 yellow epidermal dots. He had placed them iu a jar of 35° alcohol and had 

 found that those at the top were very much discoloured and that those lower 

 down were less so, those at the bottom being of good colour. On placing some 

 in stronger alcohol the discoloration was intensified. He thought the discolora- 

 tion was due to the gradual decay of the central portions of large larva?, but could 

 not understand why those at the bottom were less discoloured than those at the 

 top of the jar. 



Prof. Forbes stated that he used the method described by Mr. Woodworth in 

 his laboratory and found it fairly successful. It does not preserve greens well, 

 but browns are preserved and the markings are well shown. 



Mr. John Marten said that hot alcohol was a convenient way of preserving 

 specimens by this method and that it answered equally well as killing in hot water. 



Prof. Forbes read a " Summary history of the corn plant louse. ' This was 

 an intensely interesting paper and gave the results of continued observations for 

 some years by Prof. Forbes and his assistants. It gave the life-history both 

 above and below the ground. The relations existing between the aphis and the 

 ants which were always found in company with it were explained and suggestions 

 for remedies based on these observations were made. 



The discussion on the paper was postponed until the next session. 



At the afternoon session 18 persons were present. The president called for 

 discussioa of Prof. Forbes's paper. Messrs. Howard, Riley, Fletcher and Forbes 

 discussed the points brought forward and the difficulties of getting at accurate 

 and final results were brought out. The question of possible relationship between 

 the apple plant louse and the corn plant louse was discussed by Messrs. Riley 

 and Forbes. 



