A. An outbreak is a sudden eruption or peak in a natural population. In SBW, an outbreak can occur every 20 to 30 years and last up to 20 years. However, 7-12 years is the normal duration. SBW outbreaks are currently being experienced in various locations of Manitoba. The current RMNP outbreak was first detected in June 2005.

A. Feeding activity by SBW is normally heaviest in the new foliage (needles) at the tips of branches and near the top of a tree’s crown. Spruce budworm can hasten the death of a tree by adding stress due to defoliation. Shorter periods of defoliation will reduce tree growth, but longer outbreaks can cause branches to die, and eventually lead to some tree mortality. Balsam fir is always at higher risk. It is the favoured food for the larvae and is less resistant to the effects of repeated defoliation. So far, this SBW outbreak has not caused the death of any trees in the townsite of Wasagaming.

A. Other SBW outbreaks in RMNP were recorded in 1959-1962 and 1977-1979. Although significant defoliation occurred for several years, very few trees actually died. Annual monitoring has indicated that we can expect some defoliation on all spruce and fir trees in the Park through the month of June.

A. Experts predict that the current outbreak could last several more years before returning to ‘normal’ population levels. A late frost, once SBW larvae start feeding, and predation from several bird species, could significantly reduce their population.

It is important to remember that the population cycles of SBW and subsequent outbreaks are considered part of a natural process that has been functioning for thousands of years in the boreal forests of North America. Healthy spruce trees are not likely to be killed even after several years of partial defoliation, and the mixedwood forests are expected to recover as usual.

A. There are no direct human health concerns associated with SBW. The main concern is the potential safety hazard if there are dead conifer trees in a popular pedestrian area. These trees add to the fuel load that can contribute to intense wildfires, and they can sometimes fall during high winds, threatening public health and property in the vicinity. Park staff have been trained to identify, assess and remove hazardous trees in high visitor use areas.

The main complaint will be the red/brown colour of conifer trees from the loss of some of their needles. Some trees could die if they are subject to numerous stress factors, such as overcrowding and lack of moisture. The trees will look “sick” with red and missing needles. Also, the worms hanging from trees on thin threads may bother some people walking under the trees.

A. A Spruce Budworm Management Strategy was developed in 2006 and includes actions related to communication, monitoring, and management intervention (if required). For the summer of 2011, the monitoring program will be continued to track the status of this SBW outbreak. This will allow us to predict defoliation levels for the next spring. Some preventative actions, such as targeted removal of high-risk or dead trees and thinning of dense stands to reduce competitive stress, will also be considered.

A. Pesticide application will reduce defoliation during a spray period. However, once a spray program stops SBW can return and defoliation will increase again. The pesticides used for SBW control can kill all butterflies and moths in the sprayed area, reducing biodiversity and affecting pollination of flowers. A spray program for the Wasagaming area would cost between $50,000 and $60,000 per year.