Key Features
- Brown leader and or branches
- Gummy wounds at branch joint
- Gray- green caterpillar feeding in sap
Symptoms
In the spring, leaders of infested trees wilt and curve downward to resemble a shepherd's crook or fish hook. In older trees, wounds caused by these caterpillars are found all along the trunk where branches are joined. Wounds are gummy and white, often covered with white crumbs of caterpillar excrement and sawdust. If you break open the gummy mass you will either find the greasy gray caterpillar, its excrement or just an abandoned feeding tunnel. Growth above infested terminals is often poor in comparison to healthy trees. Branches joined to the main trunk at infested whorls or tree tops can be girdled and killed. Gummy wounds produced along main trunk between branches is caused by the less common pine pitch mass borer.
Biology
Young caterpillars winter in a shallow pit that they dig in the bark. When the weather warms in early April, caterpillars crawl out of their resting place along the exposed bark surface to either the tip of the leader, or to where the branches join the central trunk. When it bores into the bud of the leader it chews its way down to the whorl causing the shepherd's crook. When it bores to where branches join the central trunk, it produces the gummy wounds, sometimes girdling or killing limbs or tree tops. Once in the tree, it feeds until it makes a cocoon in July. In August, adult moths emerge and lay eggs on the tree trunk. Young caterpillars feed on bits of bark until they dig their shallow pit where they spend the winter.
Management Recommendations
Sanitation or the removal of heavily infested trees can greatly improve your ability to manage this pest. Adult moths will often lay eggs on old wound sites, or nearby trees. Reducing tree stress will help trees resist attack. Chemical controls with a long lasting broad-spectrum insecticide are most successful when applied in early April before the weather warms. This kills the young caterpillar as it crawls from its overwintering sites to bore beneath the bark.
Effective Pesticides
Active Ingredients include: Bifenthrin, Chlorantraniliprole, Permethrin
