While there’s always something to do in the garden at any time of the year, winter tends to be a bit more subdued. Our plants are dormant or safely sheltered from the cold, our seeds for next year are just starting, and we may be safe and cozy inside with our indoor plants. Nature continues on, however, and just because things look quiet doesn’t mean nothing’s happening. In hidden nooks and crannies, in beds of leaves and under the soil, life goes on in the winter garden. For this blog we’ll take a brief look at what insects do in winter, how our winter gardens provide shelter to beneficial insects, and how the life cycle of bugs affects the plants around them. Let’s dig in!
Insects and Temperature
Unlike warm-blooded creatures—including humans—insects cannot regulate their own internal temperatures. They rely on the environment to do that, which is why a particular cold winter can reduce bug populations and a warm winter can cause them to rise. Evolution is a clever process, however, and many species of insects have found ways to survive the winter months until they can become active again in spring. So how do they do it?
That answer depends on the insect in question. Many bugs have adapted their life cycles to fit the seasons, so that they’re in a dormant phase when it’s cold outside. Moths and butterflies are good examples of this; their pupae/cocoon phase often happens over the winter. The baby moth or butterfly is safe from the elements—they often make their cocoons in sheltered spaces including piles of fallen leaves—and while dormant their bodies produce chemicals that help keep them from freezing. As it turns out many species of insects do this, including gallflies, houseflies, many types of beetles, springtails, and budworms. The chemicals in question vary with the species, but some do actually produce natural ethylene glycol, the same chemical that’s in the antifreeze in many cars.
Not all species can produce anti-freeze chemicals, so they rely on other strategies to stay alive when it’s cold out. Ants, being colony insects, work together to help survive the cold months. While different species of ants (there are thousands of different ones) have different survival strategies, many ants do something similar: they eat as much food as they can to prepare for hibernation and then retreat into their tunnels deep beneath the ground to stay warm. The whole colony huddles together in a semi-dormant state until things warm up again.
Bees are some of our favorite insects—they’re beneficial to any garden space and frankly just fun to have around. They also have some adaptive strategies for dealing with winter weather, and interestingly enough honeybees and bumblebees do this in very different ways. Honeybees stockpile food for the winter in their hives—that’s what honey is actually for—and then as things cool down the entire hive huddles in one big mass around the queen. They’re not hibernating per se; they still get up to eat food and expel wastes from the hive. But they devote most of their energy to staying warm until the weather improves and they can start gathering pollen again. Bumblebees take a different approach—they prefer nesting in the ground or in fallen leaves left over from autumn. The leaves and other debris provide an insulated nest that keeps them warm and safe until they can re-emerge to start pollinating our gardens again.
For some butterflies, moths, and other flying insects, the solution is far more simple: they fly to warm climates during the winter. Monarch butterflies are most famous for this, with epic migrations and large colonies forming in parts of Mexico during the winter. Many other species migrate as well, so if you’re seeing an unfamiliar type of butterfly in your garden in the fall they might just be en route for their migration.
Supporting Overwintering Insects
Our gardens are part of the natural world, and we owe it to nature and to ourselves to be good citizens with respect to our fellow living creatures. Helping overwintering insects in our outdoor garden spaces can be as easy as postponing fall and winter cleanup until after spring begins. Many wonderful species of bugs—including butterflies, fireflies, and bumblebees—nest in fallen leaves and other fall debris. By leaving those on the ground until spring, we provide our insect friends with warm and safe places to spend the winter. When mulching our garden beds or landscaping, using a lighter, leaf-based mulch can help ground-wintering insects dig the nests they need to stay warm—heavy wood mulches can block their access to the soil and keep them from finding shelter. If you have seed producing flowers, consider delaying deadheading them until spring as the stalks can provide nesting places for beneficial insects and the seeds left in the flower heads are good food for many species of birds. With a little planning, our gardens can be a source of joy not only for us but for the species with whom we share our world, and we can all enjoy a safe and cozy winter with the promise of spring to come.
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