Why you'll likely see low-flying helicopters across Toronto this month

Helicopters are set to spray neighbourhoods across Toronto and the GTA to get rid of insects that destroy and weaken trees.

The pests, called European Gypsy Moths, were brought to North America from Europe and Asia in the 1860s for silk production experiments. They ended up spreading, feeding on trees, and in some cases, completely stripping them of their leaves. This makes trees more susceptible to disease and harm from other insects.

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From mid-May to mid-June, the city will deploy two helicopters to spray an area of roughly 3,336 acres with Bacillus thuringiensis subspecies kurstaki or Btk, a naturally occurring bacteria found in soil.

The spray is only toxic for certain kinds of caterpillars and doesn’t affect adult moths, butterflies, other insects, birds or mammals.

The helicopters will release the pesticide 15 metres above treetops in various neighbourhoods, including parts of Etobicoke, High Park, Rosedale and Casa Loma. Each time, the aerial spraying will start at 5 am and last until around 7:30 am.

The city is also asking residents to take matters into their own hands. The steps to manually remove Gypsy Moth eggs include getting up close and personal with the insects — so it’s not for everyone. But if you’re not squeamish, there are steps that can be taken before mid-May.

You can tell if your trees have Gypsy Moths if you see small holes in leaves, if only the veins of the leaves remain, or if trees look bare. If that’s the case, depending on what stage they’re at, you can either remove the eggs or the caterpillars before they become moths.

Clumps of their eggs can be collected, removed and destroyed. Or, you can tie a burlap sack around your tree. The caterpillars will crawl to the parts that are shaded and then you can take down the sack to get rid of them.

Good luck!