Autumn is here, the temperature is dropping, and the leaves are falling. As colder weather arrives, animals get ready for winter in several ways, including migration, hibernation, going dormant, or remaining active. It may come to some’s surprise that a large number of insects overwinter here in Ohio. Some overwinter as adults, while others may overwinter as larvae or chrysalis/cocoons. Insects that die prior to winter often leave behind an egg sac or larvae that will be ready come springtime. Since insects are ectothermic, or “cold-blooded”, those that overwinter here must enter diapause/dormancy. Occasionally, some will use a freeze-avoidance method, and find somewhere warm (like your home) to spend the winter. Thankfully, a large percentage of our insects brave the winter outside.
When an insect’s body notices the change in temperature, diapause will automatically set in and their metabolism will slow down dramatically. Insects that survive the winter through diapause, can do so using various techniques. One way is when an insect “fattens” up and then their metabolism slows down. Many can also create their own “antifreeze”, called glycerol, that they can flood their body with. This keeps the insect from freezing, helping to ensure their survival through the winter. Another technique that insects may use is called “supercooling”. Supercooling occurs when an insect gets rid of all the food and water molecules in its body, in order not to freeze. Water has to have some type of particle to attach to, in order for ice crystals to form. If there are no particles present, then water can cool down to -36.58°F without freezing. By eliminating any food and water in the insect’s system, there are fewer particles that can freeze.
Whatever fascinating method(s) is used, many insects also rely heavily
on the insulation of fallen leaves for cover. Bumble bee queens burrow under the top few inches of soil to overwinter, but need the extra protection from the fallen leaves to survive. Several moth and butterfly species overwinter as caterpillars, using the fallen leaves for shelter. Other butterflies and moths, including the beautiful Luna moth, overwinter as cocoons or chrysalis. When mowing leaves to mulch them or bagging them and tossing them in the trash, you risk accidentally disposing or destroying these insects. Various other organisms, including spiders, snails, and worms also need the leaf cover. These provide food sources for small mammals, birds, amphibians, and reptiles through the winter.
According to the EPA, leaves and yard waste account for up to 33 MILLION tons of waste that enters landfills every year. When organic waste breaks down in a landfill, without the presence of oxygen, it produces and releases methane. When methane enters the atmosphere, it has 20x the warming effect as Carbon Dioxide. Methane drives around 25% of the current global warming. Leaving the leaves to decompose naturally not only keeps them out of landfills, but will also provide your soil with nutrients and improve water retention.
If you’re like me, this is a fabulous reason to NOT have to do more yard work. However, some may not like the idea of completely letting their yard go wild. That’s ok, you can still provide the protection that these insects need to survive by raking your leaves into a designated area in your yard that you let go wild. Then once spring rolls around, make sure you don’t clean up TOO early. Some insects may start emerging in April, but others wait for warmer temperatures that typically come in May. This year’s leaf cover will provide protection against late-season frosts.
I encourage you to put down the rake and leave the leaves. It’s one of the simplest and most valuable ways you can support local wildlife. And, since you won’t be spending all that time raking leaves, now you can start that book you’ve been wanting to read or start that hobby you’ve been wanting to get back into. It’s a win for you, and a win for wildlife!
