Endangered New Jersey: Where Do New Jersey Moths Go in the Winter?

We have all heard stories about the incredible migrations of monarch butterflies every year. But where do moths go in winter?

In New Jersey winters, most moths don’t migrate far away like monarch butterflies do. They survive the cold in various dormant stages right where they live. This process is called overwintering.

Many overwinter as caterpillars. Some species spend the winter as larvae — often tucked in leaf litter, soil, or under bark where they pupate (form cocoons) and stay protected until spring.

For example, the Polyphemus moth caterpillars burrow into the ground to overwinter as pupae. Some giant silk moths also pupate in soil or leaf litter in fall and remain dormant through the winter.

Overwintering as pupae is one of the most common ways moths survive cold weather. The caterpillar forms a cocoon in fall and stays in that state underground, under leaves, or attached to plants until temperatures rise in spring.

Luna Moth (Actias luna)
American moon moth
via Wikipedia

Overwinters as a Pupa in a cocoon under fallen leaves on the forest floor

They might also overwinter as eggs. Certain species lay eggs in the fall that remain dormant through winter and hatch in spring. For example, the invasive spongy (gypsy) moth overwinters as egg masses attached to tree trunks, fences, rocks, or other surfaces until spring.

A few overwinter as adults. Though most adult moths die when winter arrives, a few hardy species can be seen on warm winter days. For instance, the winter moth (a non-native species) can emerge from the ground on mild nights to mate, and mourning cloak butterflies (a relative, not exactly a moth) may occasionally bask in the sun in winter.

Moths and their immature stages seek refuge in places that protect them from freezing temperatures. Leaf litter and soil offer insulation and moisture buffering. Under tree bark or logs is also a protected microhabitat against wind and cold.

Cocoons are generally in hidden spots, and pupae may be camouflaged in dry leaves or hooked to twigs.

Of course, the moths that give the species a bad name may be overwintering in man-made structures. For pest species, clothes moths and pantry moths can stay active inside homes if warm conditions allow it.

But for the good pollinating species outdoors, it helps to leave some natural debris. If you rake up all leaves and stems in your yard in fall, you remove many of the places where moths and other beneficial insects overwinter. Leaving leaf litter and plant stems undisturbed helps native species survive winter better.