180 THE CANADIAN ENTOMOLOGIST. 



its legs, and this power it retained for two days, after which -it was lost 

 sight of. The same powder was applied to a full-grown grasshopper ; 

 immediate uneasiness was manifested, and within two minutes its hind legs 

 were partially paralyzed so that they could not be used with much effect. 

 The first symptoms were a general rubbing of the legs against each other 

 and a peculiar backward movement of the body ; in four minutes there 

 was a trembling of the whole frame, while all the legs were so much 

 affected that locomotion was very feeble. In six minutes the insect had 

 lost all control over its limbs, and in nine minutes it was on its back with 

 no power to recover its natural position. - A second patient manifested 

 precisely similar symptoms, but was not affected quite so rapidly. Applied 

 to house-flies in a room, some of them begin to fall powerless in two or 

 three minutes ; others will remain active several minutes longer, but mani- 

 fest constant uneasiness, evidenced in unnatural movements of wings and 

 legs, and a frequent thrusting out of the proboscis. Having operated in 

 a room one day about noon, I swept up after a few minutes several hun- 

 dred flies and put part of them in a tumbler covered with a small plate, 

 and the remainder in a chip box which I carried in my pocket for the first 

 day, where the flies would receive some warmth from the body. After 

 five or six hours the box was opened, when several crawled out or flew 

 with a very weak, short flight ; these were evidently recovering ; the 

 others remained on their backs, many of them moving their legs now and 

 then. At the same time those in the tumbler were looked at ; all were 

 on their backs, but still alive. In twenty-four hours afterwards those in 

 the glass were in the same helpless condition, barely alive, while in the 

 box three more had so far recovered as to be able to walk, and one of 

 them could fly a little. The following day they were examined again and 

 every one of those in the box were dead, while in the tumbler out of 137 

 there were 22 alive, which number was reduced to three the following 

 day ; this small remnant survived two days longer, when all died. 



In the use of Insect Powder on the green Aphis which infests house 

 plants, the same course was observed ; the insects dropped from the 

 plants as if paralyzed, and after a short time were incapable of loco- 

 motion. After two days they were found still alive, but in this instance 

 there was no sign of recovery in any of them, and all died within two or 

 three days afterwards, but whether from the direct effects of the powder 

 or from starvation I was unable to decide. 



When I addressed you last year I referred to a strange disease which 



