It may shade into dark brown with blue or black sections infested by staining fungi. After maturing in the bark, new adult beetles bore their way out and fly off to attack another pine. It may well be. During the summer, spots with no stage 1 trees are not likely to expand because attractants are no longer present. Check to see if the spot is expanding in more than one direction.
Large spots can have more than one active head.
Determine the number of stage 1 and 2 trees. For large spots that have more than 50 trees, it is not necessary to examine each tree. Just walk the boundaries and estimate the number of these trees in the spot. A 10-factor prism is useful for this purpose. Using the Control Priority Guide from the next section of this handbook, determine the control priority for the spot.