What Insect Is Threatening Pine and Spruce Trees?

Driving through Northern Ontario is beautiful. Towering pine and spruce colour the landscape a brilliant green and scent the air with their fresh, spicy perfume. Or at least that’s what it used to be like. Now, you are just as likely to see a landscape of greyish-brown scruff; the ghosts of the verdant trees that grew for up to 1000 years. What happened to the forests in Northern Ontario? It is an invasive species called the spruce budworm.

What Is the Spruce Budworm?

The larvae of the spruce budworm feed primarily on mature spruce and fir trees, though they are classified as needle-eaters. A close cousin of the spruce budworm is the jack pine budworm. This budworm variety contributed to the deforestation of jack pine stands 20 years ago. This two-toned voracious eater is dark khaki green on the top and tan underneath with a black head and two rows of light spots.

The spruce budworms seem to hover in thin air as they descend from the canopy on invisible threads. Budworms will grow to 1 inch long before they create a pupa. The pupal stage will last about one week before they emerge in July as small, moths that are grey or brown in colour. The female will mate within a week of hatching. They lay egg masses on the undersides of needles.

Each tiny larvae spins a cocoon around itself initially. They emerge about 10 days later and quickly begin doing damage to their host trees. They spin webs around newer needle shoots to hold them together while the larvae eat the base of the needles. Their air ballet occurs when they have decimated the needles and have to look for more on another level of the tree.

What Are the Symptoms of Infestation?

The first signs of a potential outbreak are the webs that cluster the needles together. However, those can be difficult or impossible to see from the ground. As the budworms feast, the partially consumed trees turn reddish-brown and look scorched as if they’d survived a fire. Some green can still be seen closer to the trunk, but the further out the needles go on the branch, the worse their condition.

Despite looking like they have sustained mortal damage, they may take up to two years to die. The damage is worst at 2 to 3 meters, or between 9 and 10 feet. The tops of the trees will actually fall off. Once that happens, it is inevitable that the spruce budworms have moved on to spread damage nearby.

What Is Being Done to Combat Them?

Forest health technicians have been attempting to map the infestations. However, the pandemic has put a significant dent in progress. As work resumes, there is hope that aerial inspections will allow them to create a more detailed map of the infestations. The Minister of Natural Resources has been working on some options to combat the spruce budworm spread.

Bacterial insecticide applied in an aerial spray program is one option to cut down on the budworm population. Using a tree removal service to fell damaged trees or moving tree harvesting efforts to damaged areas first are other methods that may make an impact in the spread.

Since the spruce budworm is a native species, there is also some hope that natural enemies can make a difference. Wasps and flies often prey upon spruce budworm eggs, larvae and pupa, and some birds make a meal of young and adult budworms. Still, this type of natural predatory combat can take a very long time to make an impact.

Rely on Experienced and Knowledgeable Professionals for Your Trees’ Care

When your trees are showing signs of distress, you need someone who understands what they are trying to say. Martin’s Tree Service was founded in 2009 by an arborist, and that focus, passion and commitment for trees have fueled our teams ever since. When you need help, contact us for all your tree service needs.