Sept. 3. I9I7 Quassia Extract as a Contact Insecticide 501 



Washburn (46) reports that a spray solution consisting of quassia 

 extract and soap, barring the expense of the chips and the time consumed 

 in the extraction, is recommended for the hop aphis in Oregon. 



Gould (14) ascertained that a quassia extract solution not containing 

 soap was inefficient for the San Jose scale on pear trees. 



Fletcher (11, 12) reports that the decoction prepared in the propor- 

 tion of 78 pounds of quassia chips and 7 pounds of whale-oil soap to 100 

 gallons of water is the standard remedy for the hop aphis in Ontario, 

 and also that it has given most satisfactory results against other aphids 

 with no injury to the foliage of the trees treated. 



Howard (17), discussing the experiments of Celli and Casagrandi, who 

 determined that the fumes from quassia wood kill aerial mosquitoes, 

 summarizes the conclusions' of the Italian authors as follows : 



It is, however, to be noted that for these odors, fumes, or gases to exercise their 

 culicidal action they must fill or saturate the whole ambient ; otherwise they produce 

 only apparent death, or at most only a culicifugal action, which sometimes in houses 

 may be useful in protecting man from being bitten by mosquitoes. 



Piper (35) reports that a decoction prepared in the proportion of 28 

 pounds of quassia chips and 7 pounds of whale-oil soap to 100 gallons of 

 water is used almost exclusively for the hop aphis. He says: 



It is quite as effective against other species of Aphis. The whale-oil soap without 

 the quassia is of somewhat less efficiency. 



Henderson (15) determined that a strong decoction of quassia without 

 soap was ineffectual upon the apple aphis in Idaho, but when soap was 

 added to it and the mixture was then diluted and applied warm the result 

 was that nearly all of the aphids were killed. 



Theobald (44), writing about the apple sucker (Psylla mali Schm.) in 

 England, says: 



The only preventive we find of any use is spraying with quassia and soft soap as 

 soon as the buds commence to svv'ell and the lar\'se are seen to be coming from the eggs. 

 We usually use 6 or 8 pounds of soft soap and 8 pounds of boiled quassia chips to the 

 100 gallons of soft water. 



Boucart (2, p. 376), compiling formulas and results obtained therefrom 

 by several authors, cites six insecticides having a quassia basis. These 

 are variously concocted, some being decoctions and others infusions, but 

 each one contains soap, and, furthermore, one contains alcohol, one 

 petroleum emulsion, and one carbolic acid. The originator of the one 

 containing petroleum emulsion recommends it for destroying various 

 caterpillars infesting fruit trees. The authors of the formulas containing 

 only quassia extract, soap, and water say that these insecticides kill 

 Cochylis ambiguella Hiibn. (cochylis of the vine), the hop aphis, wheat 

 aphis, green aphids, woolly aphis, peach aphis, gooseberry aphis, 

 Phytopius ribis W., and Phyiocoris miliiaris Westw. (orchid bug). 



Parker (32), in the laboratory sprayed branches of prune trees bearing 

 prune aphids {Hyqlopierus pruni Fab.) with a solution made by extracting 



