10 BULLETIN 1201, U. S. DEPARTMENT OF AGRICULTURE. 



and had a slight effect on bees (No. 109, Table 1) and tent cater- 

 pillars, and on Aphis spp. A and B (No. 502, Table 2) ; used as a 

 decoction (No. 502a, not filtered), it had no effect on the same species 

 of aphids (Table 3) ; used as a fumigant (No. 502), it killed only 

 75 per cent of the Macrosiphum sp. O tested, besides the one lady- 

 beetle and one of the five large webworms tested; and used as a 

 stomach poison, it was efficient but slow against grasshoppers and 

 silkworms (No. 109, Table 1). 



The hot and cold water extracts, alcoholic extract, and distillate 

 from white hellebore were efficient but slow against silkworms, al- 

 though a 0.5 per cent solution of veratrine in weak sulphuric acid 

 killed the silkworms more quickly. The alcoholic and benzene ex- 

 tracts, used with soap (Nos. 508 and 517, Table 4) , were inefficient 

 against four species of aphids (Aphis spp. A and B, Macrosiphum 

 sp. A, and M. liriodendri) . 



The powdered roots of white hellebore and the hot-water extract 

 of these (not commercial) were found efficient but very slow against 

 silkworms, although they had no effect on rose aphids. 



COMPARATIVE RESULTS DISCUSSED. 



Powders dusted upon or fed to six species of insects. — Reference 

 to Table 1 shows the following: Of the five powders dusted upon 

 roaches, sabadilla and pyrethrum kill quickly and seem almost 

 equally efficient; derris has no practical value; and since hellebore 

 and amianthium, although efficient, kill so slowly, they can not be 

 recommended as satisfactory roach poisons. 



Relative to the four powders fed to and dusted upon grasshop- 

 pers, all were efficient, but only pyrethrum killed quickly, and for 

 practical purposes none of these can replace the arsenicals as grass- 

 hopper poisons. 



Of the five powders fed to and dusted upon silkworms, only derris, 

 amianthium, and pyrethrum killed quickly, although hellebore and 

 sabadilla were efficient but slow. 



Relative to the four powders used against flies, pyrethrum seems to 

 be the best dust, but derris is a close second. Used as a stomach 

 poison, amianthium killed all the flies tested within four or five 

 clays ; and amianthium used as a dust killed all of them within four 

 days. 



Of the three powders dusted upon honeybees, sabadilla and amian- 

 thium killed them comparatively quickly, while hellebore acted 

 slowly. 



Of the three powders dusted upon potato-beetle larvae in a potato 

 patch, pyrethrum acted the most quickly, although all the larva? 

 dusted with derris, "cube," and pyrethrum were dead within 24 

 hours. 



Powders dusted upon aphids. — Reference to Table 2 shows the 

 following: Used as dusts, sabadilla, amianthium, and hellebore had 

 no practical value against two species of aphids (Aphis sp. A omit- 

 ted for these powders). Pyrethrum was efficient against all five 

 species of aphids tested ; while " cube " was efficient against four out 

 of five species, and derris against three out of four species tested. 



Powders used as fumigants, decoctions, infusions, and hot-water 

 extracts. — Reference to Table 3 shows the following: Used as fumi- 



