You rifle the phone book for an exterminator as you think how you ll miss sitting in its shade, enjoying its yellow foliage. Maybe there s something else going on here. A strong happy tree will be able to manufacture and transport Bad Tasting Stuff to repel the particular brand of insect that is dining on it. It will endure some loss due to insect feeding, but will be able to keep the balance in its favor. There is even more to it than that.
Insects have ways of homing in on weakened trees from great distances.
They can pick out an unhappy tree from a group of dozens of happy ones and several flagpoles. Let s think back on that white pine. It doesn t matter. The point is that human activity had compromised the root system in the past, resulting in the demise of the tree years later. Sawflies or no, that pine was doomed.