Frequently Asked Questions

The spruce budworm is an insect native to the forests of Quebec, which means it has been present here for several thousand years. It is a member of the lepidoptera family, which means that it appears as a caterpillar in its larval stage and then transforms into a butterfly in its adult stage. The larvae cause damage by feeding on tree needles, causing defoliation. A reddish tinge may be visible after one year of moderate or severe defoliation on affected trees.

Btk is a naturally occurring bacterium in soil, water and vegetation. This bacterium has been isolated from the ground for use as biological insecticide. Its insecticidal power arises from the fact that during its growth cycle, the bacteria produces spores and crystals that are, after ingestion, transformed into a toxin by the alkaline conditions of the targeted insect’s intestine. Btk biological insecticide is specific to insects of the lepidoptera family. In effect, lepidopteran larvae have a alkaline digestive system and receptors that specifically allow the crystalline protein to bind itself and poison the insect. An amount of about 1.5 litres per hectare is sprayed on the targeted forests. Registered by Health Canada, Btk Biological Insecticide is recognized worldwide for its safety towards non-target species.

The regions of Quebec currently affected by the epidemic are Bas-Saint-Laurent, Saguenay-Lac-Saint-Jean, Capitale-Nationale, Abitibi-Témiscamingue, Côte-Nord, Gaspésie-Îles-de-la-Madeleine, Chaudière-Appalaches and Outaouais.

The MRNF, which is responsible for the detection of insect epidemics, uses several complementary approaches to detect SBW infestations: the network of terrestrial observation sites for detection using pheromone traps, the inventory of hibernating larvae (L2), annual damage assessment (surveys by air and land) and remote sensing. The participation of forest users is also very useful, reporting any insect outbreak event. The MRNF conducts an air inventory every year towards the end of the summer to determine the damage caused by SBW in the forests of Quebec. This inventory allows to visualize the impact and progress of the SBW epidemic in Quebec.

On average, if we look at the evolution of previous epidemics, an outbreak of SBW lasts 15 to 20 years in one place. The air sprays last about 10 to 15 years in the same region.

Btk aerial sprays are not aimed at stopping the epidemic, but are intended to keep trees affected by the SBW alive. Stopping the epidemic is rather the result of the interaction of several non-exclusive factors, such as lack of food, death of tree hosts, parasitoids, predators, diseases and climate. In general, this is a gradual process whose main regulatory factors of SBW populations negatively influence the fertility and survival of the insect pest.

The balsam fir is the species most vulnerable to the spruce budworm. Next are the white spruce, red spruce and black spruce. The Norway spruce is also vulnerable to the spruce budworm, but this is less well documented. Larvae can also be seen on other species, such as larches. Hardwoods and pines are not affected by this insect.

Wood can be used if the tree is alive or if it died recently. However, if the tree has been dead for more than two years, the wood is no longer usable due to degradation caused by secondary insects and mushrooms.

First, ensure that the tree is affected by the SBW and not by another insect or disease. The guide for woodlot owners produced by the MRNF can help you minimize the impacts of spruce budworm on your land. It can be found at: https://cdn-contenu.quebec.ca/cdn-contenu/forets/documents/GM_epidemie_TBE_boise_MFFP.pdf?1646923697 It is also possible to apply Btk, an effective biological insecticide to control the spruce budworm. This insecticide is available for individuals on the market.

Aerial spraying against the SBW epidemic occurs between late May and early July. The periods of operation, that is to say the periods when spraying is carried out, are in the morning (between 4 a.m. and 9 a.m.) and in the evening (between 6 p.m. and 9:30 p.m.), every day (7 days a week) if the weather is favourable to spraying.

Spraying insecticide by air requires specific conditions for optimal success. Indeed, spraying must be carried out when wind is low, the foliage dry and in the absence of rain. These conditions are usually present in the early morning and at the end of the day.