By now, temperatures are regularly dipping below freezing and cold autumn rains with (gasp!) even a snowflake or two mixed in make venturing into the garden less than appealing. But if you haven’t cleaned up all your spent perennials or the last of the leaves, give yourself permission to leave it all behind. If you leave things a bit messy, the birds and beneficial bugs will thank you. There’s no longer any reason to be out there with freezing fingers and nose; sit by the fire and read a good gardening book or move your tools into a warm garage or shed and give them a final scrub and oiling before putting them away for the winter.

If you have seedheads left on dried flowering plants, they’re a bird’s buffet. Numerous North American songbirds eat seeds: finches, sparrows, chickadees, buntings, jays, nuthatches, blackbirds, grosbeaks, etc. One stop in a messy garden packed with dead, seed-filled, native flowers equals a smörgåsbord for both resident and migratory birds. Gardens rich in shriveled fruits and abundant seedheads help these migratory birds survive not only winter, but spring breeding. I vividly recall once watching a huge flock of cedar waxwings making a ruckus one grey March day as they feasted on the remaining crab apples that clung to the branches of trees in the park across from the Camden Library. The brown fruits were a feast for them. In a similar fashion, even though we fill the feeders regularly around our home, many birds will pass them by in favor of the much-despised burdock, whose seedheads are the plague of my existence, catching in my hair and sleeves as I pass by them, but attractive to bees in summer and everything from titmice to turkeys in winter.

Butterflies also utilize gardens for overwintering, finding thick piles of leaf litter, a chunk of tree bark, or other cavity to nestle into. When you leave your gardens messy, including ignoring the dried leaves on plants, you help to encourage a rich population of native butterflies and moths in the following spring and summer.

Butterflies develop from egg to larva (caterpillar) to pupa (chrysalis) and finally to the beauteous winged adult. Each species has evolved a strategy that allows it to successfully survive the winter in one of these four life stages. For example, swallowtails pass the winter in the pupal stage, in small brown sacs that resemble a Tootsie Roll. Skippers spend the winter as caterpillars, while little coppers and blues remain as eggs through the winter. Monarch butterflies, as we know, head to warmer climes, but some others, like the mourning cloak, hunker down and spend the winter as adults.

Most temperate-zone butterflies survive the snows and frigid temperatures of New England in a stage called winter diapause, in which metabolic and respiratory rates are low and slow. To keep from freezing, butterflies reduce the amount of water in their blood by as much as 30 percent and then thicken it with glycerol, sorbitol, or other antifreeze agents. Mourning cloaks can withstand temperatures down to minus 80 degrees F. Some species of butterflies produce several complete generations each summer, with the last generation entering diapause for the winter. As day length decreases over the summer, it triggers the scheduling of diapause later in the season. As there are more hours of summer sunlight in the northern latitudes than in the southern ones, northern butterflies must enter diapause earlier to prepare for the earlier onset of winter.

Butterflies whose eggs overwinter either lay their eggs on the twigs of host plants, where they remain until larvae emerge in the spring to feed on new leaves, or in the leaf litter at the base of plants whose leaves are destroyed by frost, where the larvae feed on new plant sprouts. Some butterfly species, like the endangered karner blue, rely on an insulating blanket of snow to protect their eggs from harsh weather. When there is little snow, eggs can be damaged by dry, cold air.

Adults that overwinter, such as the mourning cloak or Milbert’s tortoiseshell, store fat in their bodies in the fall. Before entering diapause, they find a place to hide such as a hollow tree or log, a crack in a rock, or inside an old building. In these protected and somewhat insulated hideouts, they enter diapause until the longer and warmer days of spring bring them forth to mate and lay eggs for the next generation. These early spring adults often have wings that are very tattered and ragged from a relatively long life of eight to ten months. Most butterflies spend only a few weeks as adults.

Messy gardens also provide habitat to a diversity of other insects. Many species of native bumble bees, mason bees, leafcutter bees, and others use garden spaces to overwinter. Depending on the species, bees will take winter refuge under a pile of bark or dried leaves, or nest in cavities in hollowed- out stems and decomposing logs. Hundreds of other critters can overwinter in gardens as well. Praying mantises, lace wings, wolf spiders, minute pirate bugs, damsel bugs, ground beetles, and ladybugs are all considered beneficial, meaning that, as a gardener, you benefit from having them around. As predators, they eat other insects, some of which can be problematic pests in our flower and vegetable gardens. Leaving layers of leaf litter for these animals to burrow under in the winter allows them to get a jump-start on minimizing pest infestations in the spring and summer. So let your garden remain a bit unkempt, slip off your muck boots, put your feet up and enjoy the late autumn free of guilt, knowing you’re providing a rich winter habitat for many forms of wildlife.