Help Garden Bugs Survive Winter Using Fallen Leaves

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 mold, fallen leaves can serve as habitat for legions of life forms, from tiny gnats and spiders to sowbugs, 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.

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 maximize 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 burlap 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.

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.

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 neighbors 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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