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Entries in Spruce Budworm (3)


Dr. Robert Wagner Invites a Public Feedback on the Spruce Budworm Report

Dr. Robert Wagner, professor of Forestry at Maine University takes a look at one of the most aggressive insects native to Maine. It is called the spruce budworm, a bug that has been responsible for the destruction of millions of spruce trees throughout Maine. Spruce budworm infestations occur in 30–50 year cycles. Between 1970 and 1985 millions of acres of forest were lost.

Dr. Wagner says that the budworm cycle is a natural part of the spruce-fir forest. However, the budworm is also something that Maine and affected areas in Canada need to stay on top of.

Since the onset of the current outbreak, the spruce budworm has defoliated trees on over ten million acres in southern Quebec.

The spruce budworm has increased steadily in northern Maine forest over the past several years. Balsam and White Spruce trees are at greatest risk. Forests at greatest risk stretch across the northern half of the state.The budworm is very destructive and alters the forest landscape every time they appear.

Over the past year, experts from the University of Maine, Maine Forest Service, and Maine Forest Products Council have been working on a risk assessment and statewide preparation plan for the coming spruce budworm outbreak. Dr. Wagner is asking the public for their comments on the report. Public comments will be taken till March 31, 2015. Please send any comments to



Maine Task Force Helping Prepare for Coming Spruce Budworm Outbreak 

The July 16, 2014 FMF blog post entitled “Preparing for the Next Spruce Budworm Outbreak” by Alison Truesdale outlined the challenges of the coming spruce budworm (SBW) outbreak in Maine. The current outbreak has grown rapidly since 2007 and has now defoliated more than 8 million acres in Quebec. Pheromone traps across northern Maine have captured rapidly increasing numbers of SBW moths since 2010, so visible defoliation of spruce-fir stands is not far off.

 To help Maine prepare, representatives from the Maine Forest Service, Maine Forest Products Council, and University of Maine’s Cooperative Forestry Research Unit have been working together over the past year. This Maine SBW Task Force includes leading experts from across the state who have been assessing the potential impact of the SBW on Maine’s forest, and developing specific recommendations for how to best prepare for and respond to the coming outbreak.

A draft report has been completed and is now undergoing internal review by the SBW Task Force. The risk assessment in the draft report indicates that 5.8 million acres of spruce-fir stands are at risk of some level of defoliation that can lead to widespread tree mortality and reduced growth. Results from two recent studies on the potential wood supply impact of the coming SBW outbreak were reviewed. These studies indicated that annual reductions in spruce-fir wood volume (or biomass) of 15% to 30% are possible from a moderate to severe outbreak, respectively.  

These studies also concluded that recovery of the spruce-fir forest following peak impact of outbreak will be slow (~40 years), and that the overall impact would be similar (both in severity and rate of recovery) regardless of when the outbreak begins.  

The good news from one of these studies is that Maine forest landowners can substantially reduce losses in spruce-fir wood volume by:

  • Adapting current harvesting to reduce the area of high-risk stands (i.e., those with high balsam fir and white spruce composition) ahead of outbreak,
  • Protecting high-risk and high-value stands with the biological insecticide B.t.k. on no more than 20% of the affected area, and  
  • Salvaging dead and dying trees where they occur.

The draft report also includes more than 70 specific recommendations for preparing for and responding to the coming outbreak by:

  • Monitoring SBW populations,
  • Managing forest stands to mitigate the impact,
  • Protecting high-risk and high-value spruce-fir stands,
  • Revising specific forest policies and regulations,
  • Addressing key wildlife habitat issues,
  • Implementing effective public communication strategies, and
  • Developing new knowledge through research.

The SBW Task Force is working now to develop a publically reviewable draft of the report later this fall. Public review and comment will be solicited during late 2014 and early 2015. 


Dr. Robert Wagner is Director of the University of Maine’s Cooperative Forestry Research Unit and Leader of Maine’s SBW Task Force. He can be contacted at or 207-581-2903 for more information about the SBW Task Force. 


Preparing for the Next Spruce Budworm Outbreak

If you are of “a certain age” and lived in Maine in the 1970s and 80s, chances are that you remember the spruce budworm outbreak then. As Doug Denico, Maine State Forester, has said, “For years, I didn’t know what a green forest looked like.”

Indeed, aerial photos of the Maine woods at that time make you think there’s something wrong with the coloring: what should be a carpet of greens is, instead, blotched brown and yellow. Now, indications are that a new outbreak will occur in Maine’s woods within the next 2 to 4 years.


Photo Image: Canadian GovernmentBetween 1975 and 1988, 20 - 25 million cords of spruce and fir were killed by the spruce budworm[1]: that’s up to 28% more wood than the current harvesting rate of spruce and fir.

Fir is actually the favorite food of the budworm, but it will also feed on white, red, and black spruce. The worm is the larval stage of a moth that is native to Maine and Canada. Outbreaks in Maine were recorded as early as 1708.  The insect outbreaks come in 40- to 60-year cycles that last approximately ten years. The larvae eat the new needles and buds of the trees, then the older needles, and then even the bark after the new growth has been consumed. After successive years of damage, the trees die.

 While the last budworm outbreak prompted forest landowners to conduct aerial spraying and salvage logging that left large clearcuts, the response this time is likely to be more measured. To begin with, there is not as much fir in the forests as there was in the 1970s. Today, there is half the biomass of fir in the forest, and 30% less spruce than in 1970.[2]  In addition, landowners and the University of Maine have sophisticated mapping technology today that allows them to determine where the highest concentrations of fir and spruce are. This will enable forest managers to precisely target methods for controlling the budworm.

Another important difference between 1970 and today is that there are now thousands of miles of forestPhoto Credit: Canadian Government management roads throughout the forest that will enable managers to access the trees on the ground. Some forest managers are already preparing for the outbreak by cutting mature fir before it can become food for the budworm.  Some pesticide use may occur, but aerial spraying, if necessary, will be limited to discrete stands with the aid of modern technology at low altitudes and slow speeds, reducing drift.

In any case, spruce and fir are not as large a part of the pulpwood markets as they were in the 70s and 80s, as the wood products industry uses more hardwood now. One thing that researchers and industry can agree on: the budworm outbreak and the resulting economic fallout will be different this time - though still likely significant - with many lessons remaining to be learned about how to manage future outbreaks.


Alison Truesdale is the Coordinator of Keeping Maine’s Forests and provides land use planning and public policy services through her company, LandForms.

[1] Assessment of Maine’s Wood Supply, Maine Forest Service, November 1993.

[2] Dave Struble, Spruce Budworm - Planning for the Coming Outbreak: Status, Monitoring and Available

Control Measures; New England Regional Council on Forest Engineering Workshop, University of Maine, Orono; March 10, 2014.