To protect natural resources, state and federal agencies across the eastern U.S. have been involved in spongy moth management for many years, using a wide range of integrated pest management tools including population monitoring, natural (biological) and chemical controls, mating disruption, and forest management practices. Because spongy moth is a nonnative pest it has few natural controls in the U.S., and none are capable of preventing its eventual establishment in Minnesota. The goal of spongy moth control is to slow its spread into new areas, delaying its impacts and the cost of management. Spongy moth is managed at a national level by the Slow the Spread program, which coordinates state cooperators on the leading edge of the spongy moth invasion. Various practices are used at different stages of population development and distance from generally infested areas.

spongy mothFemale spongy moths and egg masses on picnic table legs. Photo by the Minnesota Department of Agriculture.

What can I do?

You can play a major role in continuing to slow the spread of spongy moth in Minnesota.

  • Become familiar with spongy moth, its life cycle, and where it might be found.
  • Inspect and remove spongy moths and egg masses from your vehicles and belongings when traveling in and out of infested areas.
  • Buy firewood produced locally when visiting campgrounds or recreation areas.
  • As a business owner, make sure all imported goods arrive with the proper certification.
  • Contact the DNR for assistance when developing a forest management plan.

Forest management

There are two broad strategies to consider in forest stand management. First, stand diversity is the best means of limiting damage from any insect defoliation. Encourage a mix of tree species, ages, and size classes. Second, managing for tree health and vitality limits the number of trees dying from defoliation (no matter how diverse your stand, some defoliation still may occur). Thin overly dense stands to reduce competition. Where consistent with management objectives, harvest and regenerate oak and aspen stands growing beyond their recommended rotation age. Remove suppressed and stressed trees likely to die anyway, and create growing space for seed and crop trees. Maintain oak as an important component of the stand where appropriate and encourage other species where possible.

When and where you apply these strategies depends on your land use objectives, stand composition, and site-specific conditions. The combination of factors will determine which practices are feasible for your stand. When in doubt on the appropriate strategy, refer to Gypsy Moth Considerations for Minnesota and consult a professional forester.

Yard trees

Preferred spongy moth host tree species under stress are the most at risk of mortality following severe defoliation. Proper site selection, planting, and tree care are essential to make the most of the trees' natural defense mechanisms. A vigorously growing tree can withstand some defoliation and most weather extremes such as drought or flooding. Root disturbance or trunk injuries can lead to stress that may leave a tree prone to additional damage or death.

To keep trees healthy,

  • protect the critical root zone
  • avoid all work that may result in wounding of oaks from April to July
  • maintain proper watering and tree care
  • consult an arborist as needed

Back to top