Is 2018 a bumper year for wasps?
It's been a long, hot summer and now that August is drawing to a close, wasps are out in full force.
Pest controllers are reporting a surge in calls about wasp nests - but are we really seeing a bumper summer for the insects?
In reality, we just don't know. A lack of data on UK population numbers means that experts can't be sure of just how many wasps are out there, and in which years they have been thriving.
We do know that wasp numbers change depending on weather conditions in the spring and summer. A warm and dry spring will allow queens to make their nests and rear their workers more successfully. Mild weather also makes for more abundant food sources.
There are more than 7,000 species of wasp living in the UK, but only nine are the social wasps that upset barbecues and picnics. The common wasp (Vespula vulgaris) and the German wasp (Vespula germanica) are the two you're most likely to see, as they live all over the UK in a huge range of habitats.
Gavin Broad, a wasp curator at the Museum, says, 'If the spring weather is good, when the queens are establishing nests and it is followed by a warm summer, you'll probably get lots of wasps.'
Conditions this year have been favourable for wasp species, but experts say their numbers are likely to be within a normal range.
Chris Raper, Manager of the UK Species Inventory at the Museum, says, 'The warm, dry summer might have encouraged some social species to do quite well, but this is all part of the usual yearly cycle.
'Wasp nests reach maturity at about this time in the year, and the colonies eventually break up and bother gardeners and people with barbecues, so it is normal for everyone to suddenly notice them.'
The number of overwintering females may also affect the following year's population. Too many queens competing for nest sites could lead to the survivors being in poorer condition and producing fewer offspring.
Counting UK wasps
There are no systematic counts or surveys tracking wasp populations, so experts don't really know what an average wasp year looks like.
Some studies have suggested that wasp populations go in cycles - perhaps cycling over two years with alternative summers producing more of the insects. But some researchers have disputed this and more work needs to be done to be sure of what factors impact abundance, diversity and distribution.
Initiatives including The Big Wasp Survey are hoping to add to the data on UK wasps. Now in its second year, the survey is a partnership between the University of Gloucestershire, University College London and the Royal Entomological Society. It aims to both find out more about which species live where in the UK and discover which factors are affecting wasp populations.