By Veronica Panama | August 22, 2026
Every August, people across Canada are encouraged to check the trees around them. The annual Tree Check Month campaign, led by the Canadian Food Inspection Agency (CFIA), encourages everyone to take a closer look at tree health and watch for signs of pests and diseases. It’s also a chance to build awareness of invasive species that can put trees at risk.
Forests, urban trees, parks and natural spaces provide invaluable benefits to communities and ecosystems across the province. Tree Check Month helps protect these spaces through early detection. Invasive species can be much harder to manage once they become established, but a quick tree check can help identify potential threats early and reduce the risk of tree loss.
Invasives Species to Watch Out For
Different invasive species leave different clues. Knowing which species of concern in B.C. and what signs to look for can help you spot a potential problem early. Here are a few invasive species and signs to watch out for:
Adult emerald ash borers are narrow and elongated, with a unique metallic blue-green colour. S-shaped galleries under the tree’s bark caused by emerald ash borer larvae. Credit: Debbie Miller, USDA Forest Service, Bugwood.org (Photo 1) and Steven Katovich, Bugwood. org (Photo 2).
Emerald ash borer (Agrilus planipennis) has been detected in parts of B.C. and affects ash trees (Fraxinus spp.). Eggs are laid in bark crevices, and larvae burrow under the bark to feed. Signs of an infestation can include thinning or dying branches, yellowing leaves, a thinning canopy, new shoots from the trunk, D-shaped exit holes and S-shaped galleries under the bark. Adults are small, narrow, and metallic blue-green.
Lacy, skeletonized leaves are left behind by Japanese beetles feeding between leaf veins. Credit: Steven Katovich, Bugwood.org.
Japanese beetle (Popillia japonica) has been detected in several communities in B.C., where eradication efforts are underway to prevent further spread. These invasive insects feed on over 300 plant species, including trees, shrubs, flowers and fruit crops. Look for lacy, skeletonized leaves. Adult beetles are metallic green with copper-coloured wing covers and white tufts of hair along the sides of the abdomen.
Adult female and male spongy moths next to an egg mass on a tree trunk. Credit: Christine 123, iNaturalist (Photo 1) and Paul Abell, iNaturalist (Photo 2).
Spongy moth (Lymantria dispar dispar) has been detected in B.C., where eradication efforts are underway to prevent it from becoming established. Spongy moth caterpillars feed on leaves and can cause significant defoliation. Look for chewed or missing leaves, caterpillars, moths, tan-coloured egg masses on trunks or branches and signs of reduced tree growth. Caterpillars have a distinct pattern of five pairs of blue dots followed by six pairs of red dots along their backs. Adult females are white to cream coloured, larger than males and unable to fly. Males are brown with feathery antennae. Both adult moths have a distinct chevron marking on the wing pointing to a dot.
Asian long-horned beetle and the round exit holes it can leave in a tree. Credit: Joe Boggs, Ohio State University, Bugwood.org (Photo 1) and Gillian Allard, FAO of United Nations, Bugwood.org (Photo 2)
Asian longhorned beetle (Anoplophora glabripennis), also known as starry sky or sky beetle, was previously detected in Ontario but was declared eradicated from Canada in 2020. This invasive wood-boring insect feeds on a wide range of deciduous trees, particularly maple. Larvae feed under the bark and into the wood. Signs can include round exit holes, egg-laying spots in the bark, galleries under the bark, and frass (a sawdust-like material) around the trunk, branches or base of the tree. Adult beetles are shiny black with white spots and have long, banded antennae.
Adult spotted lanternflies showing their spotted grey forewings and a late-stage nymph resting on a tree trunk. Credit: Richard Gardner, Bugwood.org (Photo 1) and Lawrence Barringer, PennDA, Bugwood.org (Photo 2).
Spotted lanternfly (Lycorma delicatula) is not known to be present in Canada. Adults have spotted, translucent grey forewings and bright red hindwings, which are visible when they fly. Early-stage nymphs are black with white spots, while later-stage nymphs become red. Look for the insects and their mud-like egg masses on tree trunks and branches. Feeding can produce honeydew, which may also attract other insects.
How to do a Tree Check?
Now that you know some of the signs to watch for, it’s time to check the trees around you.
August is a great time to check trees, as signs of stress or damage may be easier to spot. A tree check only takes a few minutes and you don’t need to be an expert to start your inspection. There are three main places to inspect: the crown, the trunk, and the base.
Step 1: Check the crown of your tree, including the branches and leaves at the top. Look for any signs of leaf discolouration, thinning foliage, bare or dying branches or any evidence of insects feeding.
Step 2: Move down the tree and inspect the trunk. Look for cracks, holes, peeling or loose bark, unusual growths, oozing sap or areas where the bark appears damaged or discoloured. Also watch for signs of insect activity like exit holes, egg-laying sites, galleries under the bark and frass.
Step 3: Inspect the base of the tree for exposed roots, wounds, decay, frass or other changes that could suggest a problem. Exposed roots and wounds can make trees more vulnerable to certain invasives.
Invasive pests and diseases stress trees in different ways. If you think you’ve found one of these species or signs of a possible invasive species infestation, take photos and report what you find through ISCBC. If your tree check turns up other signs of pests or disease, report those concerns to the CFIA.
The Impact Goes Beyond August
Tree Check Month is also a reminder that invasive species can hitch a ride on your belongings. Before travelling, always inspect your vehicle, RV, trailer, outdoor equipment, firewood and other gear. Clean off any soil, insects and plant material, and avoid moving firewood between locations.
Invasive insects and their eggs can hide in unexpected places and travel unnoticed to new areas. Taking a few minutes throughout the year to check and clean your belongings can help prevent invasive species from spreading.
Spongy moth egg masses found in vehicle tires in the United States. Credit: Rusty Haskell, University of Florida, Bugwood.org
By learning what’s normal, watching for what’s not and reporting concerns, you can help protect forests, urban trees and green spaces for many summers to come. For more information on reporting invasive species in B.C., visit: bcinvasives.ca/take-action/report/
Happy Tree Check Month!
Veronica is an Invasive Species Coordinator at ISCBC. She values working in an inclusive and diverse environment that allows her to connect with people across Canada to discuss conservation initiatives, social resilience, and restoration topics. In her spare time, Veronica enjoys spending time in the forest, identifying species she encounters or at the beach with a book in her hand. You can reach Veronica at vpanama@bcinvasives.ca.
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