INJURIOUS INSECTS, FUNGOUS DISEASES, ETC. 177 



leaves feeding until after the middle of September, when 

 they migrate to the twigs and settle down to pass the 

 winter. 



It is very difficult to combat this pest. It has, however, 

 a number of natural enemies which sometimes exterminate 

 it before it does serious damage. The only time for carry- 

 ing on spraying operations against the insect is during the 

 fall and the winter, while the trees are in a dormant state. 

 At that time any of the soluble oil preparations will be 

 effective when used at winter strength. 



There are many mechanical methods that can be used 

 successfully in controlling this insect. Brushing with a stiff 

 broom just where the white masses appear will destroy the 

 eggs and prevent hatching. Small trees especially can be 

 treated with very good results. 



In 1904 and 1905, the Shade-Tree Commission of East 

 Orange succeeded in controlling this pest by mechanical 

 means. The trees were sprayed with water only, by direct- 

 ing a small solid jet from the power sprayer at the develop- 

 ing egg masses. A nozzle having a bore of about one-six- 

 teenth of an inch was used and the water was discharged 

 with sufficient pressure, so that when the stream was just 

 drawn along the under side of the twigs it cleared it of egg 

 clusters. The insects were dislodged and the egg masses 

 broken up, so that the larvae did not hatch. 



Wherever city water pressure is available the insect may 

 be combated by using a garden hose with a solid jet of wa- 

 ter, and as the infestation is usually on the lower branches 

 and on the under side, the method works in most cases. 



Woolly Maple Scale {Pseudococcus aceris Sign.). — This 

 insect, which attacks the sugar maple, passes the winter 

 in the larval form. The larvae are microscopic in size. 



