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The winter moth (Operophtera brumata) is usually active in its adult stage from November to January. Eggs hatch in the spring, and the larvae climb trees in order to move to other areas through a process called “ballooning,” in which the larvae produces a strand of silk that helps it catch and ride air currents.

Pest of the Month: Winter Moth

By Jesse Lee


 


What does it look like?


The winter moth (Operophtera brumata) is usually active in its adult stage from November to January. Eggs hatch in the spring, and the larvae climb trees in order to move to other areas through a process called “ballooning,” in which the larvae produces a strand of silk that helps it catch and ride air currents.


 Adult male winter moths are light brown with fringed wings, while the adult female moths are gray, wingless and flightless. Larvae are green caterpillars with a white stripe on each side of the body.


 


Host material and range


The winter moth originally comes from Europe and has been a major problem in eastern Canada, northwestern Canada, and Washington and Oregon in the United States. The pest has also recently been an issue in the eastern United States, including Massachusetts, New Hampshire and Rhode Island.


The winter moth attacks a variety of deciduous trees including maples, oaks and white elms, as well as fruit trees such as apple and cherry trees.


 


Current threat


Young winter moth larvae burrow into buds and leaf clusters to feed, eating their way from the inside out, and moving from one bud to another. Older larvae feed on the foliage, causing massive defoliation. Winter moth larvae can feed to the point of complete defoliation.


 


Prevention tips


There are several steps that can be taken to prevent winter moth infestation.


Look inside leaf clusters and buds, and search the trunk to determine if the tree is infested. Preventative insecticide and fertilizer applications can ensure tree health — a strong, healthy tree can protect itself, which will keep outbreaks at bay.


The winter moth also has many natural predators that will help control the population in the case of a minimal infestation.


 


Treatment Tips


One of the most popular and effective treatments for winter moth is application of Bacillus thuringiensis (BT). BT is a bacterium that kills winter moth larvae by eating the pest’s stomach cell layer. BT works best on young winter moth larvae.


In addition, micro-infused abamectin and bidrin materials provide outstanding results for controlling winter moth outbreaks.


Treating affected or at-risk trees with a fertilizer application including chelated minerals, magnesium and calcium will also stimulate foliar and root growth, increasing vigor in defoliated trees.


 


What can you do?


The best course of action is to determine the level of infestation and then proceed based on how serious the infestation has become. A healthy tree can often survive a small infestation, but more serious attacks will require treatment and control measures.


 


Jesse Lee is with Epic Creative, Wis. Article provided by Mauget, a leader in micro-injection and microinfusion tree care. Visit www.Mauget.com to learn more about the winter moth, steps taken to prevent and control it, and proper pesticide application and use.

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