i86 Bulletin 252. 



GREENHOUSE INSECTS. 



The nymphs are small greenish, scale-like insects found on 

 White-fly. the underside of the leaves ; the adults are minute, white, 

 mealy winged flies. Spray with kerosene emulsion or whale- 

 oil soap; or if infesting cucumbers or tomatoes, fumigate over night with hydro- 

 cyanic acid gas, using i oz. of potassium cyanide to each 1000 cubic feet of space. 

 Spray with kerosene emulsion when practicable, or fumigate 

 Green aphis, with one of the tobacco preparations. If on violets, fumigate, 

 using 3/2 to ^ oz. potassium cyanide for every 1000 cu. ft. of 

 space and leave the gas in from ^ to i hour. 



This plant-louse is harder to kill than the green aphis, but 

 JsIaCK apnis. j^^^^y i^g controlled by the same methods. 



Red-spider. Syringe off the plants with clear water two or three times a 

 week, taking care not to drench the beds. 



Violets grown under glass are often greatly injured by a very 

 Violet gall-fly.small maggot, which causes the edges of the leaves to curl, 

 turn yellowish and die. The adult is a very minute fly resem- 

 bling a mosquito. Pick off and destroy infested leaves as soon 

 as discovered. Fumigation is not advised for this insect or for red-spider. 



III. INSECTICIDES. 



M. V. SLINGERLAND AND C. R. CROSBY. 



This can be applied in a stronger mixture than other arsenical 



Arsenate poisons without injuring the foliage. It is, therefore, much 



of lead. tiscd against beetles and other insects that are hard to poison. 



It comes in the form of a paste and should be mixed thoroughly 



with a small amount of water before placing in the sprayer, else the nozzles will 



clog. Arsenate of lead and Bordeaux mixture can be combined without lessening 



the value of either. It is used in strengths varying from 4 to 10 lbs. per 100 gals., 



depending on the kind of insect to be killed. 



This is used in varying strengths, depending on the insect to be 

 Paris green, controlled and the kind of plant treated. Mix the Paris green 

 into a paste and then add to the water. Keep the mixture 

 thoroughly agitated while spraying. If for use on fruit trees, add i lb. of quick 

 lime for every jiound of Paris green to prevent burning the foliage. For potatoes 

 it is frequently used alone, but it is much safer to use the lime. Paris green 

 and Bordeaux mixture may be combined without lessening the value of either 

 and the caustic action of the arsenic is prevented. 



(For use with Bordeaux mixture only). Sal soda 2 lbs. ; water 

 Arsenite l gal- ; arsenic i lb. Mix the white arsenic into a paste and 



of soda. then add the sal soda and water and boil until dissolved. Add 

 water to replace any that has boiled away so that i gallon of 

 stock solution is the result. Use i quart of this stock solution to 50 gallons of 

 Bordeaux mixture for fruit trees. Make sure there is enough lime in the Bor- 

 deaux mixture to prevent the caustic action of the arsenic. 



