Why nests are spotted in autumn
When trees lose their leaves, nests built over the summer in branches or under eaves suddenly become visible. That is often when people notice a large hornet nest at the top of a larch or a grey ball under the chalet balcony.
Is the nest still active?
At the end of summer, the colony produces new queens that leave the nest to spend the winter sheltered elsewhere: a stump, a log pile, insulation. The workers and the old queen then die with the cold. In the Chamonix valley this usually happens in October or November, depending on altitude and weather.
- To check: watch the nest from a distance for about ten minutes on a sunny afternoon. If no insects go in or out, the nest is almost certainly inactive.
- If in doubt: don’t hit or pull down the nest. Send me a photo.
Should an empty nest be removed?
It is not compulsory. A wasp or hornet nest is never reused the following year: new queens build a new nest in spring. You can leave it to break down in the weather, or have it removed if it is in the way (under a balcony, on a façade, in an attic).
A nest left in a roof or wall will not “wake up” in spring. The spot will stay attractive, though: keep an eye on it in May and June.
The Asian hornet
The Asian hornet can keep a colony active later in the season, especially in the lowest and mildest parts of the valley, such as Servoz. If you still see hornets going in and out, the nest needs treating as in summer. See the Asian hornet page.
Getting ready for spring
- Note where a nest was built this year: queens like the same kinds of shelter.
- In May and June, watch for a single insect flying in and out under eaves and in sheds.
- A small nest treated early costs the same, but the job is simpler and safer.
A nest still active at your place? I work throughout the Chamonix valley. See prices or read the season calendar.