A single-season cycle
Common wasps, European hornets and Asian hornets all work the same way: only the fertilised queen survives the winter, sheltering in a tree stump, a log pile or roof insulation. In spring she comes out and builds a small paper nest on her own. The first workers hatch a few weeks later and the colony keeps growing until the end of summer.
In the Chamonix valley, altitude shifts everything: cold nights in May delay nest founding, and the first autumn frosts arrive earlier than in Annecy or Geneva. The risk period is shorter, but more intense.
Month by month
- Nest founding, small nests
- Fast growth
- Peak activity
| When | What happens | My advice |
|---|---|---|
| April–May | Queens leave hibernation and look for shelter: eaves, sheds, roller-shutter boxes. | Watch for a single insect flying in and out of the same spot. |
| June | Small nests of a few dozen insects, easy to treat. | The best time to act: quick, safe, few insects. |
| July | Rapid growth, first problems on terraces and balconies. | Have any nest near a doorway or bedroom treated. |
| August–September | Nests of several thousand insects, wasps drawn to sugar and meat. | Keep away from the nest and call a professional. |
| October–November | New queens leave, the colony dies with the first frosts. | An inactive nest no longer needs treating, except active Asian hornet nests. |
The Asian hornet
The Asian hornet often builds two nests: a primary nest in spring, low and sheltered (garage, shed, under a roof), then a secondary nest in summer, high up in a tree. Destroying the primary nest in May or June saves a lot of trouble at the end of summer. See my guide to the Asian hornet in the Chamonix valley.
When to call a professional
- The nest is near a door, window, terrace or play area.
- Someone allergic lives in or is staying at the property.
- The nest is inside a wall, roof or loft: it may be much bigger than it looks.
- You let your chalet or flat in season: a nest can drive guests away.
I come out 7 days a week in season across the valley, with a telescopic pole that reaches more than 15 m from the ground. Prices range from €109 to €199 depending on the height of the nest. Details on the wasp and hornet nest removal page.