Insects in winter (and why you should put away your rake)
Making a difference for insects and birds may be easier than you think!
If you are feeling overwhelmed with end-of-season yard work, I have some good news for you – you will be doing many insects, birds, and other creatures a favor if you leave the leaves, dead plant stalks, and fallen branches where they lie (or stand), and keep soil disturbances to a minimum. Though a few of our insects migrate, the vast majority stay here in Maine throughout the winter, and given the decline in many populations, it is important for them to have places to overwinter safely.
Deciduous trees evolved over 140 million years ago, and insects have been inventing ways to use the leaves ever since – and not just for food! Many native insects, including a plethora of pollinators like bees and moths, spend the winter on the ground under leaves. We may call it leaf “litter,” but for hibernating insects, it is anything but. Leaving the leaves provides critical shelter and insulation for these native bees and moths, as well as for many other insects and invertebrates. Creating a leaf mulch pile may also attract lady beetles and other beneficial insects that will be ready to support your gardening projects in the spring by controlling pests such as aphids.
Dried-up plant stalks are another likely spot to find overwintering insects. Many people are in the habit of removing them from their yards and gardens this time of year, but in fact they are of great benefit both to insects and to birds that eat those insects or the seeds of the dead plant. Some insects form galls in plant stalks, where their larvae spend the winter protected from predators and the elements, while others bore inside the hollow stems to find a cozy home.
A variety of insects also overwinter beneath protective rocks or logs, so if it’s possible to leave woody debris where it lies, this helps to ensure that creatures like woolly bear caterpillars (Isabella tiger moths) have a home for the winter. Some insects hibernate in the wood itself: leafcutter bees and the pure green sweat bee will nest in abandoned wood-boring beetle burrows. Many of these insects are able to replace the water in their bodies with glycerol when the weather turns colder, which serves as a type of antifreeze and prevents cellular damage.
There are over 4,000 species of native bees alone in North America, and more than 70 percent of them spend the winter in nests beneath the ground that their mothers created and cached food in. You can reduce the likelihood of damage to native bee nests by keeping any digging or other ground disturbances shallow.
A collection of recent scientific papers by 56 experts from around the world documents deep concerns about declining insect populations. The authors encourage individuals and governments to take urgent action to address a biodiversity crisis dubbed the “insect apocalypse.” This is a global issue, but we can all take action right in our backyards – just by putting away our rakes and leaf blowers!
- Proceedings of the National Academy of Sciences of the United States of America, “Insect decline in the Anthropocene: Death by a thousand Cuts:” www.pnas.org/content/118/2/e2023989118
- More about Leaving the Leaves: https://www.nwf.org/Magazines/National-Wildlife/2015/OctNov/Gardening/Leave-the-Leaves
- How to Create a wild bee sanctuary: https://davidsuzuki.org/queen-of-green/how-to-grow-a-wild-bee-sanctuary/
- Educational Resources about growing native plants: https://wildseedproject.net/
- A great all-around book (highly recommended by Coastal Rivers staff): Nature’s Best Hope: A New Approach to Conservation that Starts in Your Yard by Doug Tallamy