Why They Change in August

All summer

The Colony Is a Protein Factory

For most of the season a worker wasp is not interested in you at all. The colony is rearing grubs, the grubs need protein, and the workers spend their days hunting caterpillars, flies and aphids and carrying them home.

This is the part nobody gives them credit for: a decent-sized colony removes a very large number of garden pests over a summer. Through June and July, wasps in the garden are working, and they will mostly ignore you.

The workers themselves cannot eat solid protein. They are fed by the grubs, which secrete a sugary liquid in exchange for the food they are brought. That exchange is the engine of the whole colony — and it is what stops.

Late summer

The Grubs Stop, and So Does the Pay

Towards the end of the season the queen stops laying workers and the colony rears next year's queens and males instead. Those leave, mate, and the new queens go off to hibernate.

Which leaves several thousand workers with no grubs to feed, nothing to hunt for, and no sugar supply. Their job has ended, their food source has ended, and they have a few weeks to live.

So they go looking for sugar wherever it is: fallen fruit, jam, fizzy drinks, beer, bins, ice cream, the cut end of a pear on a garden table. This is the point at which most people decide wasps are a menace, and it is genuinely a change in behaviour rather than an impression.

The drunk ones

Fermenting Fruit Is Exactly What It Sounds Like

Windfall apples and plums ferment on the ground, and wasps feeding on them take in alcohol. The result is what you would expect: slower, clumsier, more erratic and considerably more likely to blunder into somebody and sting out of confusion.

It is also why late-season wasps seem to have lost all sense of self-preservation. They have: they are dying anyway, the colony no longer needs them, and there is nothing left to protect.

The practical version of this is that an orchard, a fruiting garden or an unemptied bin in September is a worse place to be than the same spot in July, regardless of whether there is a nest nearby.

What it means for you

Two Practical Consequences

A nest found in August is a bigger job in every sense except the price. The colony is at maximum size and minimum patience. The treatment is identical and it still costs £90, but the fortnight you spend deciding is a fortnight of a defended nest at full strength next to your house.

Wasps at the table in September may have nothing to do with your property. Foragers range hundreds of metres, so wasps around your food do not mean a nest in your roof. If you have wasps but no traffic going repeatedly to one point on the building, you may not have a nest at all — in which case the answer is the bins and the fallen fruit rather than a treatment. There is more in keeping wasps off the garden table.

Short answers

Wasp Questions

Going further

Wasp Guides