192 Journal of Agricultural Research voi. xvii. No. s 



EFFICIENCY OF DERRIS AS AN INSECTICIDE 



The experiments relating to the efficiency of Derris as an insecticide 

 were performed at the Insecticide Board's Testing Laboratory, located 

 at Vienna, Va.. The Derris material used was purchased on the open 

 market and is distinguished from the other materials employed by being 

 called powder derived from Derris sp. 



EFFICIENCY OF DERRIS AS A CONTACT INSECTICIDE 



The commercial powder, when used as a contact insecticide, was 

 applied in two forms: (a) as a dry powder and (b) as a spray mixture 

 with or without soap. 



DERRIS APPLIED AS A POWDER AGAINST VARIOUS INSECTS 



Dog FEEAS.^Eight dogs badly infested with fleas (Ctenocephalus cams 

 Curt.) were dusted thoroughly. The material was applied with a shaker 

 and well rubbed into the hair with the hands. At the end of 48 hours 

 no living fleas were observed. Several dead ones were seen still clinging 

 to the hairs. 



Chicken i^icE. — Twelve hens badly infested with several species of 

 lice (Mallophaga) were thoroughly treated with the powder, which was 

 well rubbed in through the feathers. When the hens were examined two 

 or three days later, they were free from lice. 



Chicken mites. — When this powder was freely dusted over the 

 chicken mites (Dermanyssus gallinae Redi) , confined in jars, all were 

 killed within 24 hours, but when used under practical conditions in a 

 badly infested chicken house, all of the mites were not killed. 



Bedbugs. — Derris was tested against bedbugs {Cimex lectularius L.) 

 by placing 20 bugs in a jar with a quantity of excelsior and then thor- 

 oughly dusting the contents of the jar. In nine tests under these very 

 severe conditions 24.4 per cent of the bugs were killed in 24 hours and 

 52.8 per cent in four days. This material would be of no practical value 

 against bedbugs. 



Roaches. — Six small cages were thoroughly dusted and 20 roaches 

 (Blattella germanica L.) were placed in each cage. At the end of one 

 week an average of 57.5 per cent of the roaches were dead, which indi- 

 cates that this material would be of very little value under practical 

 conditions. 



House flies. — In cage tests, where house flies {Musca domestica L.) 

 were dusted in ordinary flytraps about 10 inches high, all were dead or 

 inactive within 24 hours. In room tests, where the powder was freely 

 blown into the air and all parts of the room with a small hand dust gun, 

 all of the flies were dead at the end of 1 6 hours. 



