INSECTICIDES 359 



/3,/3'-Dichloroethyl ether was tested as a greenhouse fumigant and found 

 to control Aphis rumicis, red spider, gladiolus thrips, and adult whitefly. 



A survey was made of plant products for insecticidal properties repre- 

 senting some 300 species and varieties of plants. The median lethal dose 

 (LD50) for mosquito larvae {Culex quinquefasciatus) for balm of Gilead 

 (Populus sp.) buds was found to be 5.8 ppm, for filicin, a product of male 

 fern {Aspidiwn filix-mas [L.] Sw.), 11 ppm, for echinacea {Brauneria sp.) 

 root, 16.5 ppm, for sage {Salvia officinalis L.) root, 18.3 ppm, for cubeb 

 {Piper cubeba) berries, 24 ppm, for oil of sweet basil, 28 ppm, for black 

 pepper {Piper nigrum), 29 ppm, and for oil of cypress, 31 ppm. 



Piperine, the alkaloid present in the dry fruit of black pepper {Piper 

 nigrum L.), was found to be more toxic than pyrethrum to houseflies, but 

 its paralyzing action was too slow to produce the knockdouTi required by 

 Ry sprays. At a concentration of 0.10 per cent, piperine killed 75 per cent, 

 and the pyrethrins killed 51.1 per cent of the flies by the Peet-Grady 

 method. Fly sprays containing 0.05 per cent piperine and 0.01 per cent 

 pyrethrins were more toxic than sprays containing pyrethrins alone at a 

 concentration of 0.10 per cent. Thus by making suitable combinations of 

 piperine and pyrethrum in fly sprays large savings of pyrethrum may be 

 accomplished ^^■ithout reduction in toxicity or knockdown effects. 



The allyl phenols were found by Harvill and Arthur to possess insectici- 

 dal properties on houseflies. 



Several local insect control problems have been investigated. These 

 have been undertaken as the need has arisen in Yonkers, New York, and 

 vicinity. Spray residues on apple trees that had received five applications of 

 lead arsenate (4 lb to 150 gal) fell below 1.429 mg of AS2O3 per kg of fruit, 

 indicating that with normal rainfall arsenic spray residues may be kept 

 within reasonably safe limits. 



The failure to control cankerworms in a tract of woodland by banding 

 led to the discovery that the larvae are wind-borne. 



j8,|3'-Dichloroethyl ether with 0.1 per cent Tergitol 7 penetrant was 

 found to be effective in the control of Japanese beetle grubs in turf ^^^thout 

 the possibility of leaving a poisonous residue in the soil. It was found in 

 tests to control Japanese beetle adults that Tergitol 7 penetrant, a sodium 

 alkyl sulphate, can function both as a solvent and spreading agent for 

 pyrethrum resins and possesses definite toxicity of its own. 



A spray consisting of 2 qt fish oil soap and 1 qt nicotine sulphate made up 

 to 100 gal \vith water was found to be effective in the control of the holly leaf 

 miner, the most serious pest of holly in eastern United States. 



Literature Cited 



1. Association of Official Agricultural Chemists, "Official and tentative methods of 



analysis," 5th ed., 757 pp., Washington, D. C, 1940. 



2. Dills, L. E., and H. Menusan, Jr., "A study of some fatty acids and their soaps as 



contact insecticides," C. B. T. I., 7 : 63-82 (1935). 



