136 INSECTS OF ECONOMIC IMPORTANCE 



in general, Yi ounce sodium cyanide to looo cu. ft 

 for I hour repeated in ten. days is satisfactory. 

 Some greenhouse aphids ^* 



There are two aphids, the ''black-fly" (Macrosi- 

 phimi sanborni) and the green aphid (Aphis riifo- 

 maciilata) that are sometimes present on chrysan- 

 themums in large numbers and are decidedly injuri- 

 ous ; so far as known these two aphids feed only on 

 this plant and they often occur intermixed on the 

 same plant. 



The rose is subject to the attacks of two species 

 of plant lice, Macrosiphiim rosce, and Myzus ro- 

 sarum; both of them are greenish in color and some- 

 times the tender terminal shoots of the plants are 

 covered with them. 



There are also two aphids that injure violets 

 sometimes seriously; one of these, known as the 

 "black-fly" (RJwpalosiphum violcu), is often abun- 

 dant about the crowns of the plants; the other, 

 known as the " green-fly" (Rhopalosiphum persi- 

 cce), frequents all parts of the plant. 



The carnation is often badly injured by the com- 

 mon green aphid {Myzus persicce) which is so 

 abundant on greenhouse plants and many outdoor 

 plants. 



Control of greenhouse aphids — For some 

 aphids ivory soap, i pound to 6 gallons of water, is 

 a simple, safe remedy ; for others, nicotine sulphate, 

 I teaspoonful to a gallon of water, with about an 

 ounce of soap added, is efficient ; fumigation with 

 nicotine papers or some of the volatile nicotine so- 

 lutions is satisfactory if care is taken to use the 

 right amount for a given space and the house is 

 tight ; fumigation with hydrocyanic gas is effective 

 if correctly done. 



14 Davis— 27th Kept, 111. State Ent., p. 116. 



