Insects that buzzed around you all summer seem to vanish in autumn. Step outside on a cold October morning and listen: no bumblebees in the flower bed, no flies at the window, no mosquitoes whining in your ear. So where do insects go in winter? Did they fly away like the birds? Did they all die? The answer is stranger than either, and much closer. It may be right under your feet.
What happens to insects when it gets cold?
Insects are cold-blooded. Their bodies do not make their own heat, so when the air cools, they cool too, and a cold insect is a slow insect. You may have seen a fly on an autumn windowsill that can barely walk.
A few insects travel. The painted lady butterfly flies south in autumn, and it is its children and grandchildren that return to Norway the next summer. But they are the exception.
Many people believe most insects die in autumn. They do not.
The insects are not gone. They are lying still, right beside you.
Most insects enter a winter dormancy that scientists call diapause. The body almost stops: the heart beats slowly, the insect barely breathes and uses almost no energy. Some even make their own antifreeze, substances that stop them freezing solid.
Each insect has its own winter home. Ladybirds huddle in clusters under leaves and bark. Some butterflies sleep in sheds and lofts. Other insects spend the winter as tiny eggs on a twig, as larvae in the soil, or as pupae that look like dry brown parcels.
The bumblebee is the strangest of all. The whole nest dies in autumn except the young queens. Each digs a small hollow in the soil, often under moss or leaves, and sleeps there for months, alone, without eating once. She lives on the fat she built up in autumn. More hidden autumn changes are collected in autumn as a laboratory.
Try it at home: lift the leaves gently
Suitable for: 5–12 years
Think about this first. In April, the first big bumblebee comes buzzing past, all alone. Nobody flew her in from another country. Where has she been? She never left. She was in the soil, perhaps not far from your garden.
✅ A magnifying glass ✅ A white sheet of paper or white plate ✅ A stick or large spoon ✅ Garden gloves ✅ Pencil and paper ✅ A torch
- Find a pile of leaves that has lain for a while, or a rotting log.
- Gently lift the top layer with the stick.
- Put a few leaves on the white paper and look with the magnifier.
- Draw everything that moves, and everything that does not.
- Put the leaves back exactly as they were.
- Come back to the same spot in November and look again.
⚠️ An adult helps lift logs and stones. If you find a large bumblebee sleeping in the soil, cover her up again straight away.
The top leaves are dry and crackle; deeper down it is damp, dark and smells of earth. That is where most of them live. To make a winter home that lasts, see how to build an insect hotel. And why the leaves changed colour before they fell is explained in why leaves change colour.
What happens if you lift the leaves again on a frosty December morning?
Questions to wonder about
How many insects do you think are sleeping in your garden right now?
If a ladybird barely breathes all winter, is she alive or dead?
How does a bumblebee queen under the soil and leaves know that spring has come, when she cannot see the sun?
Next time you rake leaves, leave a small pile. It might be someone's bedroom.
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