124 FIRST BOOK OF FORESTRY 



trees should be cut about the middle of May ; in the South 

 this should be done earlier, in the North later. A fresh set 

 should then be cut each month until fall. Each set of 

 trap trees, with all twigs and smaller branches, should be 

 burned whenever a new set of trees has been prepared. 

 If the work is successful, the beetles are attracted by 

 the felled trees and bore into them in large numbers. 

 When the trees are taken out and the bark is burned 

 it catches the young brood, since they have not yet 

 changed into beetles and escaped. Generally these trap 

 trees catch a large number of other wood-boring vermin 

 besides the common beetles. 



The second group of dangerous forest insects, the 

 moths, differ very much from the bark beetles in their way 

 of living and behavior. 



Thus, the white-marked tussock moth, shown in Fig. 47, 

 in central New York, for instance, lays its eggs about the 

 middle of July. These eggs keep through the winter 

 and hatch the following spring, the young caterpillar 

 emerging about the end of May. The caterpillar feeds 

 on the leaves of whatever tree it may be on, and grows to 

 full size by the end of June. Then it " spins up," i.e., it 

 attaches itself to the bark on a limb or the trunk of the 

 tree and spins around itself a cocoon, in which it stays 

 as a pupa for about two weeks while it changes from a 

 caterpillar into a moth or miller. Soon after the moths 

 come out of the cocoons the female, which in this species 



