What indicates that the White Pine Weevil has infested a tree?

The presence of excessive pitch at exit wounds is a strong indicator that the White Pine Weevil has infested a tree. When the weevil larvae tunnel into the trunk or branches, the tree responds to this injury by exuding pitch or resin, which is a protective mechanism. As the larvae feed and create exit holes, the pitch builds up around these wounds, signaling the infestation to an observer. This visible response is a clear sign of the insect's presence and activity within the tree.

In contrast, formation of galls is more commonly associated with various types of gall-inducing insects like some aphids or flies, and would not specifically indicate a weevil infestation. The presence of orange spores might typically relate to fungal infections rather than an insect infestation, and red-brown pupae found on branches could suggest other pest activity or even decay processes, but they do not directly indicate the presence of the White Pine Weevil specifically. Therefore, the identification of excessive pitch at exit wounds is the most reliable sign indicative of a White Pine Weevil infestation.