496 



Since 1912 there has been a steady decline in the numbers of the 

 pest in vineyards in Chautauqua, and while all the factors causing 

 this reduction are not known, it is believed that several species of 

 Carabid beetles have exerted an important influence, the adults 

 as well as the larvae being predaceous. 



McIndoo (N. E.), Sievers (A. F.) & Abbott (W. S.). Derris as an 

 Insecticide. — Jl. Agric, Research, Washington, D.C., xvii, no. 5, 

 15th August 1919, pp. 177-200. 



Experiments on the properties of derris as an insecticide are 

 described. Though commonly known as Derris the correct botanical 

 name of plants of this genus, which belongs to the Papilionaceae, is 

 Deguelia. They are found throughout the tropics, but are more 

 abundant in the Old World than in tropical America. These plants 

 have long been known as fish poisons, for which purpose the roots 

 are pounded into a pulp. Although derris may prove useful as a 

 contact insecticide and as a stomach poison, it is of no value as a 

 fumigant. As the material must be imported, only dried roots and 

 stems are available. 



Tests were made with petrolemn ether, ether, chloroform, alcohol 

 and water as solvents, and the results show that petrolemn ether 

 is a poor solvent, while the others may be considered good, though 

 only alcohol and water can be regarded as economically useful, the 

 best results being obtained with denatured alcohol. 



Details are given of the experiments made with various species 

 of Deguelia. Alcoholic extracts of D. elliptica, D. uliginosa and 

 D. koolgibberah were generally efficient, while those of D. oligosperma, 

 D. scandens and D. robusta were only seldom so ; the powder of an 

 unidentified species mixed with water or soap solution was usually 

 efficient, while the other powders tested by this method were found 

 ineffective ; of 8 powders used as dusts, only D. elliptica and 

 D. uliginosa and an unidentified species were found efficient. 



Used as a powder derris was found to be equally effective against 

 Ctenocephalus canis. Curt, (dog flea), Mallophaga on poultry, and 

 Musca domestica, L. Dermanyssus gallinae, Redi (chicken mite) 

 was killed in 24 hours when confined in jars, but under natural condi- 

 tions all the mites were not killed. It is of very Uttle value against 

 Cimex lectularius, L. (bed-bugs), Phijllodromia {Blattella) germanica, 

 L., Pseudococcus cilri, Risso (mealy bug), Orthezia insignis, Doug., 

 Tetranychus telarius, L. {bimaculatus, Harv.) (red spider) and the 

 crawUng young of the oyster-shell scale, Lepidosaphes idmi, L., but 

 was effective against Aphis rumicis, L. (bean aphis) and Aphis j^omi, 

 De G. (green apple aphis). 



Used as a spray it proved effective against Aphis pomi under natural 

 conditions. The sprays were appHed with and without soap at strength 

 varying from 1 lb, of powder in 25 gals, of water to 1 lb. of powder 

 in 200 gals, of water. Even the weakest solution resulted in the 

 death of 98-100 per cent, of the Aphids. The soap does not 

 increase the effectiveness. Under greenhouse conditions it proved 

 effective against A. rumicis at the rate of 1 lb. of powder to 400 gals, 

 of water with the addition of soap at the rate of 1 lb. to 100 gals, of 

 water. 



