The Spotted Lanternfly: Canada’s Newest Invasive Pest

Flying in all the way from Asia, the spotted lanternfly (Lycorma delicatula) is now rapidly expanding through parts of the U.S., and some sightings have been happening right here in Ontario. This insect poses a serious threat to agriculture, because it doesn’t specialize in just one crop. It attacks grapes, apples, stone fruits, hops, maples, birches, walnuts, willows, and many ornamental plants. This means it can damage agriculture, forestry, and landscaping industries all at once.

It feeds on over 100 species of plants and trees. But it’s not just what it eats — it’s what it leaves behind: a sticky, sugary waste called honeydew that coats surfaces, promotes mold, attracts other pests, and slowly strangles the plant's health. Even worse, it travels well. It lays its eggs on almost anything — cars, trailers, lawn furniture — and spreads quietly, unnoticed, until the damage is already done.

It’s not native here, but it’s spreading fast through North America. And while it’s not widespread in Canada yet, all signs point to “when,” not “if.”

What Makes It So Destructive?

The damage isn’t from chewing leaves. Spotted lanternflies use their mouthparts to pierce trees and plants, sucking out the sugary sap. While they feed, they excrete thick, sticky honeydew that coats everything below in a shiny film, attracting ants and flies and promoting the growth of sooty mold — a black fungus that can weaken or kill plants by blocking sunlight.

In vineyards, the effects can be devastating. Lanternflies have already caused significant losses to grape crops in parts of the U.S. Their preferred host is a fast-growing invasive tree known as tree-of-heaven, but they’ll settle for maples, birch, walnut, apples, stone fruits, and dozens of others.

A Master Hitchhiker

The spotted lanternfly is what entomologists call a “hitchhiking pest.” It lays its eggs on almost anything with a hard surface: tree trunks, patio furniture, trailers, garden tools, lawnmo-

wers, firewood, bricks, stones, even the side of a camper or truck.

These egg masses, laid in late summer, look like patches of grey mud that dry and crack over time. They can survive freezing winters and hatch out in spring as tiny black-and-white nymphs, no larger than a tick. As they grow, they turn red with black and white markings, and by summer, they’ve developed wings. Adults often cluster in huge numbers, swarming the base of trees or moving up the trunk into the canopy.

From one backyard to the next — or across entire borders — the pest spreads by accident. It doesn’t fly far on its own, but it travels with us.

What To Look For

The spotted lanternfly has four major life stages. Knowing each one helps us catch it before it spreads further:

• Egg Masses (Fall to Spring): Smooth, grey, putty-like smears about 1 inch long. Often found on tree bark, rocks, fence posts, RVs, tools, and siding. As they age, they crack and darken.

• Early Nymphs (Spring): Tiny, wingless, and black with white spots. They jump when disturbed and feed in groups.

• Late Nymphs (Early Summer): Red with black and white patches. Still flightless but more noticeable.

• Adults (Mid to Late Summer): Winged and striking — brown-grey with black dots on top, red underwings, and a yellow abdomen with black bars.

Also be on the lookout for honeydew residue, black sooty mold, and a vinegar-like smell where infestations are dense.

Tree-of-Heaven: A Beacon for the Pest

If you want to know where lanternflies might show up first, look for tree-of-heaven (Ailanthus altissima). It’s one of their favorite hosts.

This fast-growing, invasive tree can reach 80 feet tall and is commonly found in alleyways, behind commercial buildings, or along railway lines. Its bark resembles the texture of cantaloupe, and its long leaves are made up of rows of smooth-edged leaflets.

If you find one, make a note. If you see one with egg masses or adult lanternflies nearby, report it. Fast.

What You Can Do

Invasive species often arrive silently, but their impact can echo for generations — through agriculture, forestry, and the landscapes we live and work in every day.

So, take a second look at that tree. Inspect the gear in your shed. Share what you learn with your neighbors. Because keeping our landscapes healthy isn’t just about planting. It’s about protecting what we’ve already got.