This article discusses the beneficial pollinators that overwinter in the garden and best practices for providing habitat for them.
As the days get shorter and the temperatures head toward freezing, many people fall back on a routine of “putting their gardens to bed” — clearcutting all herbaceous material, blowing every loose leaf and twig out of the garden and, for those with a patrician garden aesthetic, spreading a nice blanket of chocolate brown manure over each bed. While such perfection holds great appeal to the humans looking out into the garden from the warmth of their homes, pollinators view such a garden less favorably. Doug Tallamy’s seminal work in backyard ecology, the book Bringing Nature Home, implored gardeners to think about how their landscapes are viewed by the bugs and birds that rely on plants for survival.
Three-fourths of the world’s flowering plants and one-third of our food supplies depend on pollination. Pollinators need plants year-round. The succession of flowers throughout the seasons provide nectar, eggs are laid on host plants ensuring reproductive survival, plants and debris left in the garden serve as safe places for pollinators to overwinter. By planting a variety of native flowering species, and leaving them to stand in our winter gardens, we greatly add to the diversity and abundance of pollinators.
A few of the pollinators that would welcome a stay in your “messy” winter garden include:
Butterflies and Moths
Mourning cloak (Nymphalis antiopa), comma (Polygonia c-album) and question mark (Polygonia interrogationis) butterflies find a snug piece of bark or a dried leaf to nestle under until spring. These species have evolved the capability to produce an anti-freezing agent which stops ice-crystals forming in their “blood” if temperatures are below 0°C. The aptly named winter moth (Operophtera brumata), is active between November and February and the December moth (Poecilocampa populi) can be encountered even on very cold days, usually in November and December. Other species overwinter as a chrysalis. These would include cabbage white (Pieris rapae), sulphurs (Phoebis spp.), and members of the swallowtail family (Papilionidae). Hawk moths (Sphingidae) spend the winter in warm cocoons underground. Cercropia moths (Hyalophora cecropia) hibernate in chrysalis form. And still others spend the winter as a caterpillar. Examples would be red-spotted purple (Limenitis arthemis), meadow fritillary (Boloria bellona), and viceroy (Limenitis archippus) who hibernate among the vegetation, in seed pods, in silken nests, and in rolled-up leaves. The caterpillars of some species will resume feeding during mild spells. In most such species, caterpillars spend winter as individuals, but in some species they overwinter in groups. Wait until spring to enjoy repeat visits of migrating monarchs (Danaus plexippus), painted ladies (Vanessa cardui), and red admirals (Vanessa atalanta).
Bees
There are over 3500 species of native bees. Some hide away in the hollow stems of bee balm or ornamental grass. Some bury into the ground. Solitary bees don’t have colonies. They pollinate more efficiently than honeybees and are often overlooked because they do not swarm and are not aggressive. There are many varieties of solitary bees. Red mason bees (Osmia bicornis) build their nests in dry hollow stems, in walls, or in holes in wood. They readily use man-made “bee-hotels.” The larvae pupate in late summer and after emergence from the pupal stage, the young adults spend autumn and winter in an unanimated state, known as diapause, inside their nest cells. Leaf cutter bees (Megachile willughbiella) and wool carder bees (Anthidium manicatum) are also cavity nesters.
Flies
Hoverflies either hide in the soil as fully-grown larvae or they hibernate as adults in sheltered places such as the nooks and crannies of old trees. Hoverflies overwintering as adults are the ones you see flying around on the first warm days in spring, searching for aphid-infested plants to lay their eggs on, as the larvae of most hoverflies are voracious consumers of aphids.
Beetles
There are more than 400 ladybug beetles species in North America. They love to feast on aphids. Each one can eat a dozen insects a day. The alien species often get into our homes to overwinter and become pests. However, the native species only winter outside, under rocks, in hollow logs, and under leaves.
Wasps, ants, and midges are other useful pollinators.
Do Mother Nature a favor and procrastinate on cleaning your flower beds until April.
The pollinators we depend on will be rested after their stay in your garden and be ready to emerge and do their jobs again.
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