Sept. 3, 1917 



Quassia Extract as a Contact Insecticide 



515 



(a) Effectiveness of Spray Solutions Applied in Laboratory 



The aphids were collected and were sprayed as described on page 508. 

 The number used for each individual test varied from 124 to 436, with 

 253 as an average. Reference to Table VIII shows the following: Of the 

 four species sprayed, the mortality of Macrosiphum liriodendri was the 

 lowest and that of Aphis sp. the highest; the "wool" on Phyllaphis jagi 

 seemed to prevent the spray solution from thoroughly wetting these 

 aphids. From the laboratory viewpoint formulas i A and 3 A (first extracts) 

 were efficient, but only upon two of the four species sprayed. For each 

 of the four formulas the solution containing the second extract was less 

 effective than that containing the first extract, indicating that more of 

 the toxic principle was removed from the chips during the first than the 

 second extraction. Formula 3A (first extract), the one used by Parker 

 (32) on the hop aphis, was efficient upon only Aphis sp. and Chaitophorus 

 popidicola in the laboratory, but it is shown on page 517 that this formula 

 is not efficient upon the same species of Aphis outside the laboratory and 

 probably not upon C. populicola, although the latter species was not 

 sprayed outside the laboratory. 



Table VIII. — Effectiveness of quassia extracts, soap solution, and nicotine sulphate 



applied in the laboratory 



Formula No. and 

 extract No. 



Quan- 

 tity of 

 quas- 

 sia 

 chips 

 used. 



Quan- 

 tity of 

 fish- 

 oil- 

 soap 

 solu- 

 tion 

 (1.6 

 pounds 

 of soap 

 to 100 

 gallons 



of 

 ■water) 

 used 

 as solv- 

 ent. 



Length 

 of time 

 chips 

 soaked. 



Quan- 

 tity of 

 chips 

 used to 

 100 gal- 

 lons of 

 water. 



Percentage of aphids dead 9 hours 

 after application of spray solu- 

 tions. 



Macro- 

 siphum 

 lirio- 

 dendri 



on 

 tulip- 

 tree 

 leaves. 



Aphis 

 sp. on 

 blad- 

 der 

 senna 

 branch. 



Phylla- 

 phis 



fagt on 



beech- 

 tree 



leaves. 



Chaito- 

 phorus 

 popult- 

 cola on 



Carolina 

 poplar 



branches. 



I A (first extract). . 



iB (second ex- 

 tract) 



2 A (first extract). . 



2B (second ex- 

 tract) 



3 A (first extract). . 



3B (second ex- 

 tract) 



4A (first extract) . . 



4B (second ex- 

 tract) 



Fish-oil-soap solu- 

 tion (control) 



Nicotine sulphate 

 (i : 1.200 of soap 

 solution) 



Nicotine sul- 

 phate (i : 1,200 

 of water) 



Gm. 



25.0 



25.0 

 25. o 



2';.o 

 6-3 



6-3 



25.0 



C.c. 



350 



3S0 

 350 



350 

 •^ 2,000 



2,000 

 350 



Hours. 

 24 



Pounds. 

 1. 26 



1.26 

 I. 81 



1. 81 



2. So 



2.i'o 

 3- 16 



3- 16 



n In this formula the chips were soaked for 24 hours in 2,000 c. c. of water, and the soap was added subse- 

 quently. 



