As the UK braces for another heatwave, pest control experts are warning that leaving windows open at night could invite unwanted insects indoors. While opening windows is a quick way to cool down, it also provides easy access for pests, especially after dusk.
Heat Alert and Health Warning
Parts of southern England will meet heatwave criteria on Wednesday, with temperatures possibly reaching 32C or 33C, and more areas on Thursday. A yellow heat alert has been issued from 9am on Tuesday to 9am on Friday for the East and West Midlands, the south-east, south-west and east of England, as well as Yorkshire and the Humber.
The UK Health Security Agency (UKHSA) warned of possible “significant impacts” on health and social care services, including a rise in deaths among the elderly or people with health conditions, and an increase in drownings. Forecasters expect a “north-south split,” with clouds and rain continuing in Northern Ireland, Scotland and northern England.
Pests Attracted by Open Windows
John Whiteley-Wilkson, Managing Director and pest control expert at Acorn Environment Services, said warmer evenings create ideal conditions for flying insects. He said: "Many people leave bedroom and living room windows open overnight during hot weather, but they don't realise they're also creating an easy entry point for a variety of pests."
Whiteley-Wilkson explained which pests are most commonly drawn indoors: flies, wasps, moths, mosquitoes, and spiders. Flies are attracted by food and waste near open kitchens. Wasps enter due to sweet drinks and indoor lighting. Moths are drawn to artificial light. Mosquitoes breed in standing water and enter through open windows. Spiders follow the insects that gather indoors.
How to Stay Cool Without Inviting Pests
Whiteley-Wilkson recommends opening windows earlier in the evening before insect activity peaks, keeping curtains or blinds closed before switching on lights, installing insect screens on windows left open overnight, avoiding leaving food or sugary drinks uncovered, and emptying standing water from buckets and containers in the garden. He added: "You don't have to keep every window shut during a heatwave, but taking a few simple precautions can significantly reduce the number of pests finding their way inside."
