4 BULLETIN 101, U. S. DEPARTMENT OF AGRICULTURE. 



EXPERIMENTS WITH POWDERS AND OTHER MATERIALS. 



PYKETHRTJM. 1 



Tests with 28 different samples of pyrethrum have been made and 

 all samples were found to be very effective against bedbugs in jar 

 tests. 



These tests also show that there is no practical difference in ef- 

 fectiveness between powder made from the buds, half-open flowers, 

 half-closed flowers, and closed flowers, or between the cultivated and 

 wild flowers. Tests made during 1912 with powders made from 

 1908, 1909, and 1910 crops of flowers showed no practical difference 

 in their efficiency, which indicates that pyrethrum does not deteriorate 

 materially in four years. 



The actual effect of pyrethrum on bedbugs is to render the insects 

 inactive almost at once, and, although slight movements of the legs 

 and antennse may continue for several days, the insects do not re- 

 cover. 



Under the conditions of jar tests five samples, consisting wholly 

 or largely of pyrethrum stems, were found to be of comparatively 

 little value. In the one-room test made with powdered stems they 

 appeared to be absolutely ineffective. In this test a grossly infested 

 bed was thoroughly dusted, and four days after treatment careful 

 search failed to locate a single dead bug, either in the bed or on the 

 floor. Many living bugs were found in cracks where the powder was 

 still plainly visible, and some were seen crawling about with their 

 backs still covered with it. 



TOBACCO POWDERS. 



A number of tests were made with tobacco powders against bed- 

 bugs dusted in jars, and it was found that powders containing as 

 high as 3.41 per cent, 3.73 per cent, and 5.26 per cent nicotine did 

 not kill all of the treated insects in 12 days. 



HELLEBORE. 



Not one of the seven different lots of hellebore tested was Of value 

 against bedbugs. 



This would appear to indicate that hellebore is of no value as a 

 contact insecticide, and this conclusion is greatly strengthened by the 

 fact that it was found to be ineffective against 12 different species 

 of other sucking insects. 



1 A powder made by grinding to an impalpable powder the flower heads of a chrys- 

 anthemum, Pyrethrum ctnerariaefolium and P. roseum. Tve manufactured product bas 

 been sold also as " bubach," Persian insect powder, and Dalmatian insect powder. 



