PLANTS IXSECTICTDAL PROPERTIES. 



21 



Table 8. — Effects of spraying aphids with the sap and alcoholic extracts of Hura 



crepitans. 



Sample 

 No. 



Preparation. 



Insects tested. 



Esti- 

 mated 

 number 

 of indi- 

 viduals. 



Num- 

 ber of 

 sets. 



Species. 



Percentage of aphids dead 

 within — ! 



6 hours. 



2 days. 



3 days. 



500 

 500 

 512 

 500a 



500a 

 512a 



523 



524 



Sap lOper cent 



Do 



Sap 20 percent 



Sap + soap + water (5 

 per cent +4+ 100). 

 Do 



Sap + soap + water 



(10 per cent+2+100) 

 Control, soap+water 



(2+100). 

 Control, soap+water 



(4+100). 



Do 



Alcoholic extract of 



bark + soap + water 



(2+2+100). 

 Alcoholic extract of 



sawdust + soap + 



water (2+2+100). 

 Control, alcohol + 



soap+water (2+2+ 



100). 

 40 per cent nicotine 



sulphate (1/1200)+ 



soap+water (0.8+ 



2+100). 



100 

 100 

 500 



100 



100 

 2,000 



500 



100 



100 

 1,000 



1,000 



500 



1,500 



Aphis sp. A 



Aphis sp. B 



Macrosiphum sp. A. 

 Aphis sp. A 



Aphis sp. B 



Macrosiphum sp. A. 



do 



Aphis sp. A. 



Aphis sp. B 



Macrosiphum sp. A. 



.do. 



.do. 



.do. 



100 



1 Where no test was taken, and where a test continued only 2 days, blanks are left. 

 DISCUSSION OF THE LESS IMPORTANT RESULTS OBTAINED. 



A powder and decoction of the common yarrow [Achillea mille- 

 folium) had no effect on the aphids (Macrosiphum sp. B) tested. 



The roots, leaves, and stems of Columbia monkshood (Aconitum 

 columhianum) , used as a stomach poison, had no effect on grass- 

 hoppers ; and used as a dust, they had no effect on bees. 



The leaves of a peach tree (Amygdalus persica), wet with the 

 juice of mulberry-tree leaves, were fed to silkworms, and within 24 

 hours after eating this food practically all of the insects were dead. 



A water extract of ahiliton (see footnote on p. 26) had no effect 

 on silkworms. 



Cold and hot water extracts of sagebrush (Artemisia tridentata) 

 had no effect on silkworms, webworms, potato-beetle larvae, rose 

 aphids, and nasturtium aphids, but these extracts slowly killed bees. 



A water extract of ahiliton (see footnote on p. 26) had no effect 

 against small webworms and small catalpa caterpillars. Water and 

 alcoholic extracts were efficient against bees. The powder, used as a 

 f umigant, had no effect against small webworms ; used as a dust, it 

 had a slight effect on tent caterpillars and roaches; and used as a 

 stomach poison, it had no effect on webworms and flies and only a 

 slight effect on roaches and silkworms. 



A water extract of balbec (see footnote on p. 26) killed silkworms 

 quickly. 



The juice, highly concentrated, from the green leaves and beans of 

 catalpa ( Catalpa hignonioides) had a slight effect on bees. 



