126 



THE REPORT OF THE 



No. 19 



However, the insects whicli do tlie most serious technical injury to 

 trees are the Scolytidae, Buprestidae and Cerambycidge. These insects by 

 boring either in the cambium layer, sapwood or heartwood of the tree leave 

 channels which greatly lessen the commercial value of the tree. They 

 attack the living tree in the forest, the log at the drive or mill, and the 

 lumber in the yard. 



The Scolytidge work in the bark, cambium layer and sapwood (Figs. 

 62, 63 and 64) and this family is one most to be dreaded by the forester. 

 Large areas of forests have been destroyed by members of this family. It 

 would be impossible to estimate the value of timber destroyed by the pine 

 bark beetle, Dendroctonus frontalis. Its distribution seems to cover the 

 whole coniferous region east of the Rocky Mountains. An unidentified 

 species of Scolytidse has been doing some damage this season in the nursery 

 to Scotch pine. The beetle is about two mm. long and has completely 

 undermined the bark. 



Buprestidse (Fig. 65) and Cerambycidse (Figs. 66 and 67) injure the 

 stems of the tree in much the same manner. In some cases they make chan- 

 nels throughout the stem although some species work only beneath bark 

 and in the sapwood. 



Fig. 66. Cerambycid beetle (wood-borer 



Fig. 67. Cerambycid Pine-borer. 



The stems of second growth hickory {Hicoria ovata) in the vicinity of 

 Ridgeway have been badly infested with the larvae of Goes pulchra. The 

 same trees are also attacked by Dorcaschema nigrum which girdles the ter- 

 minal branches. Even after the tree leaves the forester's care it is liable 

 to insect attacks. Upon examination of some hickory lumber, which had 

 been piled so that the boards were in close contact, I found Phymatodes 

 variahilis doing great damage. Thus throughout the whole history of the 

 tree it is subject to insect injury and the amateur entomologist feels that 

 the species to be studied are almost infinite in number. 



From the systematic collector's efforts probably a large percentage 

 of our forest insects in the adult form are now in collections throughoiit 

 the country. However, this is a subject of economic importance, the forest 

 being one of our greatest resources. Very little is known concerning the 

 life history of our forest insects and only by research can the required 

 knowledge be obtained. There is a wide field for the study of forest insects 

 in relation to plant host, parasites or other enemies. Future protection 

 can only be had in so far as we have men specially trained who recognize 

 and understand the movements of these tiny foes. 



