Signs of a wasp nest: how to spot one and what to do next

A few wasps in the garden through summer is normal. A steady stream of them coming and going from one spot is not. That is a nest, and the sooner you know where it is, the easier it is to deal with.

01The signs of a wasp nest

• More wasps than usual. Wasps turning up in numbers around one part of the house or garden, day after day.
• A flight line. Wasps flying in and out of the same point, such as a gap under a roof tile, an air brick, a hole in the lawn or the corner of a shed.
• Buzzing in a wall or ceiling. A constant low hum from inside a wall, a roof void or a chimney, often louder on warm afternoons.
• Wasps indoors. Wasps appearing in a bedroom or the loft with the windows shut can mean a nest in the roof space or a wall.
• Scrape marks on wood. Fine pale lines on fences, sheds and garden furniture, where wasps have been scraping fibre to build with.
• The nest itself. Sometimes it is in plain view, hanging from a rafter or tucked under the eaves.

02What does a wasp nest look like?

Wasps build by chewing wood fibre and mixing it with saliva into a pulp. The finished nest looks like layered paper: grey, buff or brown, rounded or oval, with a single entrance hole, usually underneath. Inside are tiers of six-sided cells where the queen lays her eggs and the larvae are raised.

A nest starts in spring at roughly the size of a golf ball, built by a single queen. Once the first workers hatch it grows quickly, and by late summer a nest can be the size of a football or larger and hold several thousand wasps. Nests in wall cavities and the ground are often hidden completely, so you see the traffic but never the nest.

03Where wasps build

Wasps look for somewhere dry, sheltered and undisturbed with a small way in. Common sites include:

• lofts and roof spaces, especially near the eaves
• sheds, garages, summerhouses and outbuildings
• under eaves, soffits, roof tiles and decking
• wall cavities, reached through air bricks or gaps in the mortar
• bird boxes, compost bins, hedges, hollow trees and old rodent burrows

04Is it wasps, or something else?

Check before you do anything, because bees and hoverflies are often mistaken for wasps and need a different response. Wasps are smooth and shiny, bright yellow and black, with a clearly pinched waist. Bees are rounder and hairier. Hoverflies look like small wasps but hover in one spot, have only one pair of wings, and cannot sting. Bees going in and out of a hole in a wall or under a shed are usually best left alone: see our guide to bumblebee nests.

Very large, brown and yellow insects are more likely to be European hornets. Our guide to telling wasps and hornets apart covers the differences.

05How to find the nest safely

Stand well back, a few metres to one side of the flight line rather than in it, and watch where the wasps are heading. A sunny afternoon is the easiest time to see the traffic. Note the entry point, and whether it is high up or at ground level. You do not need to see the nest itself, and you should not go looking inside a loft or shed with an active nest in it.

06What to do once you have found it

• Keep people and pets away from the entrance, and keep nearby windows and doors closed.
• Do not block the hole. Wasps that cannot get out the usual way will find another, sometimes into the house.
• Do not spray or poke it. A disturbed nest defends itself, and wasps can sting more than once.
• Decide whether it needs treating. A nest well away from where anyone goes can often be left to die off naturally in autumn. A nest by a door, window, path or play area usually cannot.

Wasp nests last one season. The colony dies off in the cold weather and the old nest is never reused, so an empty nest found in winter is not a problem in itself.