INSECT ENEMIES OF WESTERN FORESTS 233 



location, and assists the spotters in the selection of the proper 

 trees for treatment. The two spotters cover strips on the sides of, 

 and parallel to, the course of the compass line, find, blaze, and 

 number the infested trees, and record whatever data are per- 

 tinent in regard to them. With a six-man crew there are two 

 spotters on each side of the compass man, and the chief of the 

 party follows behind the crew, working from side to side to assist 

 in the proper marking of the trees and to prevent any from being 

 missed. Regardless of the organization, the chief spotter is always 

 responsible for the character of the work performed by his crew. 



The width of the strip and the number of men in the spotting 

 crew are usually adjusted to the timber type, topography, and 

 density of the infestation. In typical ponderosa pine stands a 

 three-man crew, with each spotter covering a five-chain strip, is 

 the standard practice. This width of strip in the open timber 

 stands of this type permits the spotters to visit and closely 

 examine not only the fading trees but all that look suspicious 

 and a high percentage of the green trees as well. On the other 

 hand, in dense lodgepole and white pine stands a one-chain strip 

 is all that a spotter can efficiently cover, since it is necessary to 

 look at the base of every tree, and a six-man crew has been found 

 advantageous in such timber. When large groups of infested 

 trees are encountered, all spotters assist in marking all trees 

 within the group, even though it extends over into the next strip. 

 The spotter who has had the outside course should always be on 

 the inside during the return trip, as he is familiar with the 

 boundaries of his strip. 



The trees selected for treatment are marked in different ways, 

 varying from a blaze to a cloth or card tag tacked upon the tree. 

 When tags are used, it is a good plan to blaze and number the 

 tree on the opposite side, as this permits the relocation of trees 

 in case tags are destroyed. The data placed upon tags will vary 

 for each project, depending on what information is desired. Each 

 tree should be numbered regardless of the type of mark used, 

 so that a check can be maintained on the trees treated. After a 

 tree has been treated the tag is removed, and all tags are turned 

 over to the project superintendent at the close of the day's work 

 and checked against the serial numbers of the trees marked 

 within the area. 



BARK-BEETLE SUPPRESSION METHODS 



Methods of bark-beetle control must take into consideration 

 the varying habits of the insect species, the trees affected, the 

 locality, and the environmental conditions encountered. Methods 

 effective in one area cannot be used in other areas even against 

 the same insect because of differences in local conditions. Methods 

 suitable for the control of an insect in a tree with thin bark 

 cannot be used to control the same species infesting a tree with 

 thick bark. Differences in latitude and altitude have an important 

 bearing on the success of the sun-curing method, and the differ- 

 ences of type and forest cover will often be a determining factor 

 in the selection of a suitable control measure. It is often necessary 



