Why are there so many wasps in Denmark in late summer?

The month of August does not always bring about the sort of weather you might have enjoyed during summer’s peak in Denmark, but temperatures are still warm enough for windows to be open and for balconies to feel inviting.

But this is also an invitation for the masses of insects that have hatched and are still flying and crawling around Danish gardens in late summer.

Several insect species have, by August, spent the entire summer forming and hatching, meaning there may be twice as many as a month or two prior.

Weather conditions throughout the year in the form of a mild winter and a warm spring – as was the case in 2025 – also give optimal conditions for insect hatching.

This can make it hard to keep them out of your house or apartment, but a couple of tips will help you limit unwanted winged and six-legged visitors.

“In the pest business we call it a good insect summer, because we have lots of wasps, ants and other insects,” Claus Schultz, the head of a trade union for pest control businesses in Denmark, said in an interview with news wire Ritzau.

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“But people in their homes will understandably find all the insects annoying,” he said, adding that August is peak season for wasps.

“It’s the common wasp, also known as the yellowjacket, which pesters us most in Denmark in the summer,” he said.

“Wasps [of this type] are territorial. They attack you if you come close or disturb their nest,” he said.

If you plan to use insect spray or remove a wasps’ nest, you should therefor make sure your body, ands and face are fully covered, he said.

You can also capture or divert wasps if you find large numbers visiting you in your garden.

“Try putting something sweet like fruit juice or jam in a half-litre drinks bottle and placing in the hedge. The sweet smell attracts the wasps which get stuck in the bottle,” Schultz said.

By placing the bottle with the wide, cut-off end in the ground and the neck facing upwards, you will trap the wasps which will not be able to find their way out of the narrow end.

Other types of insects which proliferate in Denmark in late summer pest include flies and ants. These insects pose no danger but can be a nuisance when they appear in large numbers.

“If you notice flying ants in your house, you can often solve the problem just by opening the window or door. They will just fly out,” Schultz said.

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If that doesn’t work, you can try vacuuming the offending creatures. Throw the vacuum bag away as soon as you have finished.

Another insect which can be hard to remove is the silverfish.

“Silverfish often get into our homes in cardboard boxes,” Schultz said.

“That means you should avoid bringing cardboard boxes into your house. Instead, empty the box outside and throw it into the bin straight away,” he said.

Any cardboard boxes which are already in your home should also be removed.

The Danish Environment Agency (Miljøstyrelsen) meanwhile recommends vacuuming, rather than mopping floors, to prevent insects becoming attracted. That is because insects are attracted to moisture.

Vacuum cleaning also removes insects’ eggs along with dust and food particles in cracks and corners.

“The same applies when cleaning cupboards. Avoid too much moisture and keep surfaces dry,” Schultz said.

“If you’ve been cooking pasta, there will be more moisture in the house, so it’s important to air the room,” he said.

The pest control director also recommended using insect nets where possible. That way, homes can be aired out without letting the creatures in.