SPRAYING FOR INSECTS AND FUNGI. 151 



Before growth starts in the spring the eggs can be 

 largely destroyed by spraying with kerosene emulsion made 

 very strong. The kerosene and soap solution penetrates 

 the scale and destroys a large proportion of the eggs. 

 When the young insects appear in May the spraying is 

 repeated with the emulsion of ordinary strength. This 

 plan of spraying also destroys the woolly aphis and the 

 scurvy scale-louse. It is not yet certain that the spraying 

 in the dormant period with raw petroleum of good quality 

 or a good grade of petroleum will harm the trees. The 

 kill or cure methods of warring with the San Jose scale 

 has seemed to demonstrate that petroleum and kerosene 

 are not as harmful to the bark and buds of trees as had 

 been suspected, and this agrees with the writer's experience 

 on a smaller scale. But we have had more favorable expe- 

 rience on dormant trees in killing scale insects with kero- 

 sene and soap emulsion made with larger proportion of 

 kerosene than usual than with the modern pumps using a 

 mixture of kerosene and water, and far better than with 

 whale-oil soap. 



With proper care the scale-lice of the deciduous fruits 

 can be controlled largely by spraying in the dormant 

 season. But the different scale insects of the citrus fruits 

 are not so easy to manage, as the persistent foliage pre- 

 vents the use of kerosene or petroleum strong enough to 

 penetrate the scales without injury to the leaves. Some 

 of the least harmful species are kept in check by spraying 

 when the insects are exposed with kerosene emulsion, 

 whale-oil soap, or the resin solutions. But where the San 

 Jose scale joins forces with other species the tent system 

 with fumes of hydrocyanic-acid gas is the only certain 

 method. In California parties with proper outfit make a 

 business of clearing orchards of scale insects by this 

 method. Nursery stock is now also fumigated with this 



