By Kathryn Stocks

Leaving the leaves on your lawn over the winter is much more important than you might think. Somehow it is ingrained in us that we must get rid of the leaves when they fall on our lawns in the fall. We dread the work but we’ve been doing it routinely for a long time. Some people still rake but it’s become more popular now to blow them into a pile and then stuff them into bags for pickup. It’s time to break that habit.

Did you know that the majority of butterflies and moths overwinter in the landscape as either an egg, caterpillar, chrysalis or adult? Monarchs are one of the only butterflies that migrate. The butterflies that stay here use leaf litter for winter cover. Luna moths and swallowtail butterflies disguise their cocoons and chrysalises as dried leaves so they blend in with the real leaves. So it’s not just leaves you’re blowing away.

Bumble bees also rely on leaf litter for protection. At the end of the summer, mated queen bumble bees burrow an inch or two into the earth to hibernate. An extra thick layer of leaves is welcome protection from the elements for them.

Other critters that live in the leaves are spiders, snails, worms, beetles, millipedes, and more. You may think they’re expendable, but they support the chipmunks, turtles, birds and amphibians when they come searching for food in the spring.

We have to stop thinking that leaves are litter that has to be disposed of and start thinking of them as an essential part of our environment. For those who say the leaves will ruin their lawns if left where they fall, lawns actually benefit from a thin layer of leaves. The lawns alone have no redeeming value for our little critters and insects. In fact, lawns are like an urban desert for them.

But if you feel you must keep your lawn clear of leaves, try using a rake or a leaf vacuum to capture whole leaves rather than blowing them or shredding them with a mower. Shredding also destroys the overwintering creatures. The whole leaves can go into a leaf pile in a corner of your yard or right onto your gardens. They provide valuable organic matter for your plants and are as good as wood mulch for weed suppression and moisture retention. Plus they’re free and the colourful fall leaves look so pretty in the gardens.

So please think seriously about leaving the leaves when they fall this year. You’ll be doing nature a favour.

Woolly bear caterpillars overwinter in our leaves

As I was researching my story on leaving the leaves, I discovered that the woolly bear caterpillar is one of the critters that nestles in the leaves for the winter. We’ve all seen these fuzzy black- and brown-banded caterpillars on our walks at this time of year and you have to admit they’re pretty cute.

Woolly bears are the larval form of the Isabella Tiger Moth, which emerges from the cocoon in early summer and lays eggs that hatch in late summer or early fall. The caterpillars then feed on whatever leaves they can find. These critters spend the winter as caterpillars so at this time of year they are on the move, eating and looking for that perfect pile of leaf litter to curl into for the coldest months.

So how do woolly bears stay alive during an icy Canadian winter? They hide in the leaf litter under the snow and go into a type of hibernation. Their furry coats help to insulate them and keep them warm, and they also produce a natural antifreeze that allows them to survive in extreme winter conditions.

In the spring, woolly bears thaw out and return to their wandering ways, eating leaves and later pupating in cocoons.

Caterpillars that hibernate are extremely rare, so leave some leaves on your lawn or in your garden to make sure they’ve got somewhere to stay this year.