SOME INSECT PESTS OF THE ORCHARD. 147 



Scurfy scale and the Oyster Shell scale on the other hand pass 

 the winter as eggs under this armor-like covering. The lime 

 sulphur when applied to these forms seems to loosen the scale 

 from the bark, which allows the wind to blow them off along with 

 their numerous eggs. 



Plant Lice, or Aphides. These forms winter as eggs on the 

 twigs. The little black, shiny specks seen around the buds on the 

 twigs and the lenticels on the bark of the trunk during the dor- 

 mant season are the eggs of these forms. In the spring these 

 hatch and, reproducing very rapidly, are able to do a lot of 

 damage by sucking the nourishment from the growing leaves 

 and the blossom buds. In our experimental work we have found 

 that a nicotine product, called sulphate of nicotine, is an almost 

 perfect plant louse insecticide. It has given much better results 

 than kerosene emulsion, whale oil soap, or any other of the con- 

 tact insecticides. Unfortunately this product cannot be made at 

 home. It is a commercial product, and is put on the market under 

 such trade names as "Black Leaf 40," "Black Leaf 20," "Nicoti- 

 cide" and "Sulphate of Nicotine." 



Combination Sprays. It is very fortunate that we do not 

 have to spray for insects and diseases at separate times. Almost 

 always it is best to make a combination of fungicide and insecti- 

 cide. Lime sulphur used at the summer strength, (1 to 40) is a 

 fungicide. Arsenate of lead, used at the rate of 2i/2 pounds to 

 three pounds of the paste, or ±14 to 11/2 pounds of the powder, in 

 a fifty gallon barrel of liquid, is an excellent insecticide for biting 

 insects. These two can be combined making an excellent spray. 

 If plant lice are present when this spray is to be used one-half a 

 pint of Sulphate of Nicotine can be added to the spray liquid in a 

 fifty-gallon barrel. In a combination of this kind, therefore, we 

 have a material that will kill the disease, a material that will kill 

 the eating insects, and a material that will act on the sucking 

 insects. This is as near the ideal spray as we can hope to get. 



The number of sprays to use during a season would probably 

 average three. Unless scale insects are present we never recom- 

 mend the use of the dormant spray of lime sulphur. For scab, 

 plum curculio and plant lice this combination spray should be 

 used first as the blossoms begin to show color. The second spray 

 should be given just as the petals have fallen, and the third spray 

 should be given three or four weeks later, or in case of plums 

 just as the fruit begins to show color. 



