Warm weather may lead to an increase in household flies, but an insect expert has shared a simple technique for catching them without the need for sprays or swatters. Dr. Jessica Stokes, a Project Officer and Fellow of the Royal Entomological Society, advises approaching flies slowly and from above.
Flies possess excellent eyesight, particularly for detecting movement. Their instinct when sensing danger is to move upwards. This behavior is the basis for Stokes's recommended method: aiming a few inches above the fly's resting position rather than directly at it. As the fly attempts to escape upwards, it will fly into the hands that are closing in the space above.
This technique capitalizes on the fly's ability to sense rapid changes in air pressure and movement. When threatened, they instinctively launch themselves upward to take flight.
According to Dr. Stokes, periods of warm and humid weather can accelerate insect development, leading to a noticeable increase in fly populations. As people open windows and doors to cool their homes, flies find more opportunities to enter. Fruit flies, in particular, are attracted to warm, humid conditions and are often found near fruit bowls, sinks, drains, and compost bins.
While flies can be a nuisance indoors, they play a vital role in outdoor ecosystems as pollinators and decomposers, breaking down organic waste and recycling nutrients. Experts suggest capturing flies and releasing them outside rather than killing them.
Dr. Stokes highlighted the importance of insects, noting that they perform crucial natural functions. The goal, she explained, is to help people better understand insects and find ways to coexist, keeping them out of homes while allowing them to thrive outdoors where they contribute to pollination, decomposition, and serve as a food source for other species.
For those looking to deter flies from entering their homes, Dr. Stokes recommends using citrus peels, whose scent insects find overwhelming. Peppermint oil can also be effective by masking food odors and insect trails that flies rely on. A few drops of peppermint oil in water can be sprayed around doorframes and windowsills, or cotton balls soaked in the oil can be placed in problem areas. This scent needs to be refreshed every few days as it fades.
Dr. Erica McAlister, Principal Curator for Diptera and Siphonaptera at the Natural History Museum, added that flies might seek refuge from intense summer heat indoors. She suggests installing screens, such as bead curtains, to prevent flies from entering in the first place. Dr. McAlister also mentioned that while she personally ushers flies out by waving, for situations with many flies, catching them in pots by moving very slowly is another option.