Help Garden Bugs Survive Winter Using Fallen Leaves

, written by Barbara Pleasant us flag

Fallen leaves stored in paper bags

Nature can be slow to reveal her secrets, and how we treat fallen leaves is a good example. Count back three decades and most people burned their leaves, simply wanting to get rid of them. Then came the age of shredding and composting, methods meant to speed the transformation of leaves into mulch or humus-rich compost.

But these days, concern about insect decline is making us rethink how we deal with leaves. Before they become compost or leaf mould, fallen leaves can serve as habitat for legions of life forms, from tiny gnats and spiders to woodlice, springtails and salamanders. Some moths and butterflies overwinter as caterpillars hidden deep in fallen leaves, while others hide out as cocoons. Where I live, a stand of wild violets that gets covered with a thick mulch of leaves is an ideal habitat for Great Spangled Fritillary butterflies – one of the showiest native butterfly species.

“Great
Larvae of Great Spangled Fritillary butterflies overwinter in leaf mulch

Leaf Pile Bug Habitats

In 2016 I wrote about jumping in leaves as a way to crunch down an oversize leaf pile, but the insect advocates at the Xerces Society recommend keeping leaves intact to maximise their value as invertebrate habitat. Shredded leaves may contain more dead insects than live ones.

There is also a difference in the type of cover provided by whole vs. shredded leaves. Whole leaves hold more air pockets, and wet, stuck-together leaves are a dream world for tiny critters. I like to pile leaves on vacant beds and then cover them with hessian or another porous cloth held in place with boards to keep them from blowing about. The covered whole-leaf mulch keeps the soil below from freezing, even when blanketed with several inches of snow.

Outside of the cultivated garden, a space in the shade where leaves and pine needles are allowed to collect year after year can serve as a sanctuary for solitary bees and other insects, and you can gather decomposed material as you need it in the garden. In a permanent leaf pile that weathers to 4 inches (10cm) deep in summer, you can dig down with gloved hands and harvest fistfuls of stringy “duff” to add beneficial fungi and bacteria to potting composts.

“Leaf
Leaf mulch insulates better and won’t blow away when covered with a weighted cloth

Earth-friendly Options for Storing Leaves

You may need to bag up some leaves, because there are always some that need to be collected to keep walking surfaces safe or to prevent drainage ditches from clogging. A few years ago when I visited a big municipal composting facility to see how they handled the city’s leaves, I was horrified by the problems caused by plastic bags, which become ragged flyaway pieces that must be filtered out. Paper bags do not pose this problem, and some recycling programs provide paper leaf bags to residents. Switching from plastic to paper bags solves a huge problem for composting facilities, and some no longer accept leaves bagged in plastic.

I keep all of my leaves, and have found that I like using paper bags to store leaves I set aside to cover food waste in the composter or to use as fresh litter in the chicken coop. I also use stored leaves to pave over packed ice or to relieve muddy conditions near the bird feeder in winter. When tightly packed and stashed in a dry place, leaves stored in paper bags stay autumn-fresh for months.

“Parsley
Whole leaves make a good winter mulch for parsley and other cold-hardy vegetables

Limit Leaf Blowing

Noisy and smoky, gas-powered leaf blowers need to be retired, and the same goes for older electric leaf blowers, which can be extremely loud. People who use low-noise leaf blowers should do so sparingly and at times when neighbours will not be bothered, and only for jobs where nothing else will do. I use a battery-powered leaf blower to clear leaves and pointy poplar seeds from my deck and house gutters, and to herd leaves from a section of sloping pavement. That’s about as much windblown dust as I care to breathe.

Besides, I could be blowing out this year’s overwintering generation of moths, butterflies, and little crickets and beetles. While we’ve come a long way from burning fallen leaves, we have yet to unlock all of the secrets held in a leaf pile.

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Comments

 
"I left leaves in some garden beds last fall. Now I have perennials starting to come up. When do the bugs come out of hibernation? Can I get rid of the leaves yet."
Lynn Thompson on Wednesday 20 March 2019
"I have the same question that Lynn Thompson posted 2 years ago. I would love to see that answer. I left leaves in my garden beds over the winter. When do the insects emerge? I don't want to remove the leaves to early. It is starting to warm up a bit here in NE Ohio and everyone seems to be bagging their leaves again! Thank you,"
Mary E Gill on Sunday 21 March 2021
"I usually wait until I see a few of each insect in the garden, a few bees, a couple of butterflies and see the ladybugs again and then I tidy up....The other thing is never use a leaf blower, just do it slowly and gently by hand and leave the leaves in a pile for a couple of days before you bag them up just so that anyone that is still in there can leave at a slower pace. "
Susie Hughes on Monday 22 March 2021
"These are such good questions! I think it's best to move leaves before the insects hatch in spring if the leaves are in the garden as winter mulch. Some of the creatures in leaves are not garden friendly, as I learned by growing potatoes in minimally disturbed leaves. The insects in leaves are best off in uncultivated areas anyway, where they can decompose in their own time. "
Barbara Pleasant on Sunday 27 November 2022
"In spring I turn the leaves into the soil. They help create a lighter, loamer soil, and hold moisture. Leaves contain trace elements plants need. The deep, dark, moist soil under a pile of leaves is black gold!"
Jayne Runyan on Monday 16 October 2023

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