522 Journal of Agricultural Research voi. x, no. lo 



aphids, and the insects afterwards were apparently not affected. For 

 this solution to be effective it must be sprayed upon the insects, and since 

 it can not reach the nervous system in any form other than as a fine spray 

 carried by the air, it is believed that death occurred as a result of some of 

 the fine spray being taken into the respiratory system while the solution 

 was being applied. This view agrees with the one that some of the fine 

 spray which is carried by the air passes into the operator's mouth, 

 thereby causing a bitter taste. 



At this place should be mentioned quassiin extract as a stomach poison 

 for bees and files. A large quantity of quassiin, extracted from the quas- 

 siin powder and then dissolved in sugar sirup, was fed to 250 honeybees 

 (Apis mellifica L.) in observation cases. At no time was a symptom 

 observed which could be attributed to the effects of the quassiin, and these 

 bees lived practically as long as controls fed sugar sirup not containing 

 this insecticide. These results agree with those obtained by Illing- 

 worth (18, p. 160), who fed sweetened quassia-extract solution to flies 

 (Rhagoletis pomonella). He says: 



The flies ate the sweetened, bitter liquid freely, but no harm came to them. 



It should be noted, however, that Brande (3) in an early textbook states 

 that quassia is an effectual stomach poison for flies. 



(d) Effects op Water Extract of Quassia Chips 



Fifty grams of quassia chips were soaked in i ,000 c. c. of water for 24 

 hours; this proportion is about equal to 44 pounds of chips to 100 gallons 

 of water. At 8 o'clock many rose aphids, fall webworms, and larvae of 

 the potato beetle (Leptinotarsa decemlineata Say) were sprayed with the 

 above solution; at 11 o'clock few of the aphids were apparently dead 

 and many of the webworms were inactive; at i o'clock all of the aphids 

 and webworms were apparently dead, but only a few of the former had 

 fallen from the plants; all of the potato-beetle larvae had fallen to the 

 ground, some were apparently dead and the others were so affected that 

 they could yet move their legs but could not crawl; at 4.30 o'clock all 

 of the insects sprayed were apparently dead. The following morning 

 several of the aphids and practically all of the potato-beetle larvae had 

 revived, while the webworms were slowly recovering from the effects of 

 the spray- On the second day after being sprayed, most of the web- 

 worms had become normal. 



(e) Effects of Soap-Solution Extract op Quassia Chips 



In the preceding paragraph and on pages 512 to 513 it is shown that 

 strong water extracts of quassia chips do kill aphids when properly 

 applied, but it is also shown on pages 514 to 515 that weaker extracts 

 containing soap solution are really more effective. As a rule, while the 

 inefficiency of quassiin dissolved in water may be attributed to the poor 



