Unwanted Guests

Insects frequently affect the beauty and health of our trees. Few who experienced the gypsy moths’ devastating impact will forget the sight of barren tree canopies in May.

Now, as we forecasted last year, another insect threatens deciduous trees.

Winter moth (Operophtera brumata) is a newly introduced pest in Massachusetts. Populations have been increasing and affected areas have grown rapidly. Winter moths feed on a wide range of hosts including apple, crabapple, cherry, maple, oak, and blueberry.

Dr. Joseph Elkinton, a forest entomologist at the University of Massachusetts, studies the winter moth. He estimates that infested areas average 2000-3000 females per tree, each producing up to 150 eggs. That’s a quarter million or more, per tree.

After eggs hatch in early spring, the larvae (caterpillars resembling green inchworms) tunnel into and forage inside buds before bud break occurs. Delayed bud opening due to cool weather conditions can lead to increased damage. Just a few years of partial defoliation can lead to branch mortality. Complete defoliation leads to tree mortality.

While the potential for overwhelming damage is great, winter moths can be effectively controlled. Preventative treatments require precise timing, beginning in early spring before leaf and flower buds open.

Consulting with leading entomologists keeps us abreast of the latest innovations in tree care. We use bio-rational materials. We find this class of insect control products provides superior pest control with minimum disruption of beneficial insects and other organisms.

We have sent tree protection recommendations to clients in areas where we expect high winter moth activity. If you have seen evidence of this insect (past defoliation, green inchworms, or moth flight in December), please contact your HG or a certified arborist to discuss strategies for protecting your landscape trees.