187 



in the green pods growing on the same plant upon which they them- 

 selves were bred. In midsummer, most of the adults emerge within 

 three or four weeks after the crop is harvested. Where later seed 

 crops are grown, it is therefore advisable to stack the early crops as 

 soon as possible, thus preventing the free emergence offered by leaving 

 the crop in shocks on the field. Where bur clover is abundant and 

 matures its seed-pods in early spring, they should be destroyed by 

 burning the fence lines in the spring. This can frequently be done 

 after the plants mature and before the lucerne seed crop comes on. 

 This paper concludes by pointing out that organised effort is required 

 if Bruchophagtis funebris is to be efficiently controlled. 



Parker (W. B.). Quassiin as a Contact Insecticide.— C/. S. Dept. 

 Agric, Washington, D.C., Bull. no. 165, 31st December 1914, 

 8 pp., 1 fig, 2 tables. 



From investigations in California, the writer believes that quassiin 

 ■could be cheaply prepared and possibly sold at a lower price than some 

 of the materials now on the market. Quassia chips, commonly used in 

 preparing spray solutions for the control of the hop aphis, Phorodon 

 hiwiuli, Schr., are the wood of Picrasma excelsa, Swz., the Jamaica 

 quassia, which is stated to be available in considerable quantities. To 

 •determine the insecticidal value of quassiin, its action was compared 

 with that of nicotine sulphate of a known strength. Soap bark solution 

 had to be used instead of whale-oil soap as the spreader, since the latter 

 killed some of the aphids. Prune twigs infested by P. hamuli and Hyalo- 

 pterus pruni, ¥., and set in moist sand were sprayed with a compressed 

 air spray machine ; the insects that were killed were readily obtained 

 from this and counted. The table of results given shows that quassiin 

 used at the rate of 6| oz. of 40 per cent, solution to 100 U.S. gals, was 

 almost as effective as nicotine sulphate, 6| oz. to 100 U.S. gals. The 

 percentage of quassiin in quassia wood varies ; supposing it to be075 

 percent. only,l|lb.of chips would be needed for 100 U.S. gals, of spray; 

 if, for safety, 3 lb. be used and 3 lb. whale-oil soap, the total cost of 

 materials per 100 U.S. gals, is 1 shilling. Allen's method for extracting 

 quassiin was used in its preparation for the experiments and is as 

 follows : — Quassia wood is exhausted with hot water and the liquid 

 precipitated with neutral lead acetate. Sulphuretted hydrogen is 

 then passed through it to remove excess of lead, and after filtration 

 the solution is shaken up with chloroform, which dissolves out the 

 quassiin and may be removed by decantation. On evaporating the 

 chloroform, the quassiin is obtained in a more or less crystalline 

 condition. It is readily soluble in alcohol, and when the alcoholic 

 solution is boiled, a precipitate forms, which was filtered off and the 

 filtrate evaporated to dryness on a water bath, the resulting dark 

 resinous material being extracted with boiling water. When cool, this 

 was again extracted with chloroform, evaporated down and made into 

 solutions of standard strength. Even when diluted to 1 part in 5,0D0, 

 it was effective as an insecticide. It seems probable that an impure 

 form of quassiin, soluble in water, could be prepared by extracting 

 it from the wood with a solution of sodium carbonate, more cheaply 

 than by Allen's method. 



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