THE FOREST NURSERY 



353 



* One or more sides open. 



6. Protecting the Nursery from Injury by Insects. A large 

 variety of insects infest nursery soil and feed upon the roots of 

 the growing trees, while many others feed upon the tender branches 

 and foliage. Only those species are mentioned which occur more 

 or less frequently in forest nurseries in large numbers and cause 

 serious damage. It is the duty of the forester to watch his seed- 

 beds and transplant beds for evidences of insect injury. As soon 

 as harmful insects appear they should be destroyed. Prompt 

 action is usually essential. 



Annihilative measures should vary somewhat in each case de- 

 pending upon the habits of the insect concerned, the kind of trees 

 and the season. The life history of the insect determines at what 

 stage in its development its destruction can be accomplished. 



Leaf-eating insects are easily destroyed by spraying the trees 

 with arsenate of lead used in the proportion of 1 pound of 

 the chemical to 12| gallons of water. The arsenate should con- 

 tain at least 14 per cent of arsenic oxide and not more than 50 

 per cent of water. When used in the above proportion it will 

 not harm the tenderest foliage even when applied in midsummer. 

 Grasshoppers have been successfully combated at the Page nurs- 

 ery by applying a mixture of Paris green in moist bran. A 

 mixture of Paris green, manure, salt, and water, known as the 

 Griddle mixture has been successfully used against grasshoppers 

 at other nurseries. The seedbeds can be protected against them 

 by using screens with f- to ^-inch-mesh. 



The larvae of moths sometimes injure the buds of pine and other 



