INSECTICIDES. 185 



numerous as to individuals, may be overlooked ; but 

 they are the future centres of fresh companies. 



Pots plunged for a few moments into water heated 

 to 140° Fahr. will kill most insects ; and probably in no 

 case the treatment will injure the plants. Syringing 

 with a weak solution of soft soap, that is, two ounces to 

 the gallon of water, is efficacious. The potency of this 

 wash is increased by boiling in it two ounces of flowers 

 of sulphur. Sulphur, indeed, is the most important 

 ingredient in the various washes offered to the public 

 as insecticides. 



A cheap solution of calcium sulphide may be easily 

 prepared by boiling together — 



Flowers of sulphur . . 1 lb. 



Caustic lime . . .2 lbs. 



Water ... .4 gallons. 



To prepare the liquid for use take of the above, 



Calcium sulphide . 4 ounces 1 -mt-. n 

 c ,, r > Mix together, 



sort soap . . 2 ounces ) & 



Add hot water . 1 gallon. 



Stir and allow to settle. 



When cold, this liquid may be used as a bath, or 

 sprinkled by the syringe or by the garden hand- engine, 

 or by a brush ; this last instrument most effectively 

 rubs the solution into buds and bark infested by 

 Aphis. 



Some have strongly advocated a copious syringing 

 of infected trees, when the thermometer is seven or 

 more degrees below the freezing point. No injury is 

 done to the trees by thus using the above solution ; 

 " but the freezing and thawing loosens and clears the 

 Aphis eggs out of innumerable crannies."* 



Smoke of all kinds has a sickening effect on 

 Aphides ; and the old plan of fumigation by the slow 

 combustion of coarse and wetted tobacco is very con- 

 venient in glass houses and forcing-frames. 



MM. Monestier and Lauland recommend placing an 



* E. Ormerod, ' Manual,' p. 288. 



