Vol. 18 Issue 4, Winter 2013
By Emily Bzdyk
In the late fall, plants die back and leaves litter the ground. As the weather turns cold and your backyard looks increasingly lifeless, you may be tempted to tidy up those garden beds. But there are many reasons why you should wait till “spring cleaning” time to clean up any plant material from your garden or till the soil. Winter gardens are alive with unseen creatures, waiting out the cold to reawaken and start over.
There are many small animals that use the garden as a hidden refuge for the winter months. Besides the more obvious mammals and birds you might see picking over the garden for seeds, there are small invertebrates such as insects which hide themselves or their eggs there. When an insect overwinters, it is known as diapause. Different kinds of insects may overwinter as adults, larvae, pupae or eggs. Some adult or larval beetles spend the winter in the garden soil and reawaken when the weather warms. Bumblebee colonies taper off in the fall, but the queen survives in small animal burrows and restarts the colony in the spring. Many other native bees nest in the ground or in dead plant stems and overwinter in garden settings.
Those roaming woolly bear caterpillars you observe in the fall often find a garden with a patch of dead plants and leaves to overwinter as larvae. Their bodies literally freeze solid, and they survive by producing special substances called crypoprotectants to protect their body tissues. In the spring they thaw and pupate. Other caterpillars pupate in the fall, and either build cocoons and hide in the soil or insulating vegetation, or hang out in the open on stems and branches in a camouflaged chrysalis. These moths and butterflies emerge as adults in the spring.
Even if insects and spiders die in the fall, they will leave their eggs in the garden to overwinter and start the next generation in the spring. You may find balls of silk suspended in webs where spiders left their eggs. Insect eggs sometimes look like small patches of tiny bumps or spheres, and are often left in the garden on leaves or stems of host plants.
Gardens can provide valuable winter forage for many animals. Besides the hibernating insects and other invertebrates, many other animals including birds and squirrels use the garden beds as a location to stash nuts and as a source for seeds that keep them going through the winter. On a more basic level, these seed banks also provide the next year’s flowers and plants. If plant material is removed and burnt or bagged and thrown away in the fall, many seeds are lost. If the ground is disturbed, hibernating creatures and their food will be exposed and they may perish.
By leaving gardens alone until spring, you create a valuable habitat for many animals. In addition, you can observe the incredible natural seasonal changes through the winter. Leaves and dead plant materials decompose into detritus, naturally fertilizing the soil and leaving nutrients for the next year’s growth. Ice and snow covered plants and seed pods are also simply beautiful to observe on a winter day.
Insect winter ecology: en.wikipedia.org
Insect Overwintering Habits and Ecology: bugguide.net