QUASSIIN AS A CONTACT INSECTICIDE. i 
TaB.e I1.—Results of experiments with quassiin as a contact insecticide—-Continued. 
SERIES NO.3. WITH SOAP BARK ON PRUNE APHIS IN FIELD. 
Number of} Per cent of 
Formula. aphides aphides 
sprayed. killed, 
NEOPA S LO U0 CGasec 22 oS. c ee eek hha Spe tee ieyets =U Sietere ie etal ener erapet eve Rate os 1,923 97.5 
eG aioe iG KG GaS SESS SRA: Sesh ess Reece ao See eee ae Schatten, orale eis ees 721 99. 2 
CHECK SERIES. 
MWlialP-OllusoaD eS DOUNdS tO 100i¢allons: 1 feo 26.. soee teen et tees recess e oe 1,030 1284.6 
PAREN LE cee DOUMUSHLOMLOO CANONS es. 1 8 hee sien win ese cle nee ce cince nce sereeecee- 1, 202 121 
Nicotine sulphate, 0.4 grams to 2,000 cc., with soap bark, 2 pounds to 100 gallons. . 930 96.9 
1 These were the largest percentages obtained for the check materials. 
2 Tn field. 
From the foregoing table it will be readily seen that quassiin used 
at the rate of 0.4 grams to 2,000 cubic centimeters, or 64 ounces of 
40 per cent solution to 100 gallons, was almost as effective against the 
hop aphis and the prune aphis as nicotine sulphate, 0.4 grams to 
2,000 cubic centinteters, or 64 ounces to 100 gallons. The difference 
is approximately 3 per cent, while quassiin, 0.4 grams to 1,000 cubic 
centimeters, is fully as effective. 
The writer has not so far tested this material upon insects other 
than those mentioned, but believes that it will prove effective else- 
where if used in proportions corresponding to the amounts of nicotine 
sulphate that are known to be effective. 
CONCLUSION. 
Picrasma excelsa Swz. (quassia wood) is a native of Jamaica, and, 
according to data obtained, is available in considerable quantities. 
The percentage of quasslin in the quassia wood varies somewhat, 
and does not appear to be definitely known. Supposing it to be 0.75 
per cent, as given by one author, to use the quassiin at an effective 
rate of 0.4 grams to 2,000 cubic centimeters, it would take only 14 
pounds of the chips to 100 gallons of spray. To be on the safe side, 
double the amount of chips calculated to be necessary, and we have 
the following formula * and cost per 100 gallons of spray: | 
Wass chips. 0.19 per cent quassiin, 3 pounds, at $0.04. ....:..............- $0. 12 
Bae etiam sarpounds. at 60.04 222... de ncct ee tle cones eee eee e ee eee mal 
iioimcoshoumaternals per 100 gallons... .32..2.¢..---2. 252-5200 45-2-0 28 . 24 
Quassiin can be readily extracted from quassia wood, Picrasma 
excelsa Swz., in a comparatively pure form. (See p.3.) It probably 
could be more cheaply extracted in an impure water-soluble form by 
using sodium carbonate solution. The percentage of quassiin could 
be determined and the material evaporated until a standardized solu- 
tion was made. Such a material could be diluted and used with 
1 This formula corresponds very closely to formula No. 1, page 2. 
