dark green background of the surrounding forest. Infested 

 trees, the foliage of which have not changed color, are dif- 

 ficult to discover on account of their scattering occurrence, 

 Normal infestation may also "be located by the groups of dead 

 trees in the forest. A freshly infested individual tree ma;/ 

 be determined in many ways. In the first place, trees in- 

 fested by certain destrtictive species of insects which kill 

 them suddenly display distinct symptoms. In most pines the 

 foliage turns yellow. Therefore, look for yellow trees. 

 The species of tree often determines the character of the 

 symptom, as turning yellow, pitch tubes, etc., therefore, 

 methods of telling or spotting infested trees must be taken 

 up by individual species. 



Yellow pines:- In yellow pines an average of 88 per cent of 

 the infested trees can be told by the color, which is yellow 

 or turning yellow. Therefore these trees can be told from a 

 distance. A closer inspection will show pitch tubes, or ex- 

 udations of pitch with a small round hole in the center. 

 These pitch tubes, however, occur on only 45 to 70 per cent 

 3f infested trees. They may be whitish or red, depending, on 

 the spocies infesting the tree or the individual tree. Marry 

 infested trees can be told by the work of woodpeckers. This 

 consists of a scaling off of the outer layers of. bark on a 

 portion of the trunk. About 70 per cent of infested yellow 



