154 OUR NATIONAL FORESTS 



willful character, a permit is issued and the tres- 

 passer pays for the timber or special use, as under 

 regulation. Fire and property trespass cases sel- 

 dom can be construed as innocent, hence in most 

 cases such offenses result in litigation. 



Forest Insects. Protection against forest in- 

 sects is carried out in cooperation with the Bureau 

 of Entomology of the Department of Agriculture. 



An essential part of good forest protection is the 

 work of locating and reporting evidences of insect 

 depredations. There are scores of insects which 

 are constantly working in the forests, either injur- 

 ing or killing live trees or attacking the wood of 

 trees after they have been killed. Weevils kill 

 young shoots on trees and destroy tree seeds ; bark 

 beetles and timber beetles infest the bark, girdle the 

 tree and destroy the wood; and various borers and 

 timber worms attack seasoned and unseasoned for- 

 est products and destroy the wood in the forest after 

 it has been cut down and sawed into lumber. The 

 greatest annual loss by insects is caused not so 

 much by conspicuous local outbreaks as in the sus- 

 tained annual loss of scattered merchantable trees. 

 Local infestations often kill a large percentage of 

 trees on an area, but these outbreaks are easily seen ; 



