WHO KNEW Those Unraked Leaves in Your Yard are Someone’s Home?

Do you spend a lot of time raking or mowing leaves in the fall? Or maybe you pay someone to do it for you? Save yourself time and money by leaving most of those leaves in place, protecting critical overwintering habitat for beneficial pollinators and other insects, adding nutrients to your yard, and helping to suppress weeds.

How we treat our yards in the fall impacts insects that overwinter. The larvae of these insects are an essential source of food for young birds who need protein to mature, plus the larvae are easy to catch. If you care about the birds in your yard, you also need to care about the insects there.

Insects have many survival strategies and will overwinter in one of their four stages: egg, larva, pupa or adult. Some insects migrate south in the winter (think, Monarchs), and some aquatic insects overwinter under the ice, but most insects overwinter in your yard.

Native bees are our most important pollinators. 70% of the 4000 native North American bee species overwinter in the ground; certain bees build nests in tunnels, where they deposit eggs and nutrients for larvae to feed upon before emerging as adults in the spring. Other bees lay eggs in holes of logs. Bumble bee queens mate in the fall and overwinter in shallow tunnels in the ground, under a blanket of leaves, emerging to start a new colony in the spring. In addition, some bees and other insects spend their winter in hollow plant stalks, so think twice before cutting your spent flowers to the ground each fall.

Importantly, many insects modify their metabolism by entering a dormant state called diapause. When days get shorter and cooler, these insects find a winter shelter where they activate a protein that interferes with the growth of ice crystals and keeps the insects from freezing.

HOW CAN WE HELP THESE INSECTS SURVIVE WINTER? Since so many types of insects prefer to overwinter in leaves, we must take care about when and where they are raked. Disturbing leaves too late in the season may kill the dormant insects. Keep most of the leaves that fall in your yard in loose piles at the edge of your lawn, or among shrubs or flower beds. Don’t mow the leaves, as entire leaves will create larger spaces for insects. Dead-head flower stalks if you must, but leave your flower stems and seed pods uncut until spring. They add to the winter landscape, provide shelter to insects and food for overwintering birds. In the spring, before you start digging too early, be on the lookout for holes in the ground, as these may hold overwintering insects that will soon emerge.

For more information:

Northern Woodlands, article on insects in winter [https://northernwoodlands.org/outside_story/article/some-insects-in-winter-get-super-cool]

Xerces Society, Leave the Leaves Blog [https://xerces.org/blog/where-do-pollinators-go-in-winter]