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Why Are Deer Flies So Obsessed With the Color Blue? This Viral Reddit Trap Has an Answer

9:08 AM CDT on July 22, 2026

A Reddit user shared photos of their homemade blue deer fly trap.

A Reddit user shared photos of their homemade blue deer fly trap.

|Images via Reddit/videogametes

A homemade blue bucket coated in sticky adhesive, shared by Reddit user u/videogametes on the r/mildlyinfuriating community, has become an unlikely sensation after the user claimed it dramatically reduced attacks from deer flies while walking outdoors during the summer.

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The post features two images of a DIY trap. The first showed a blue plastic bucket coated in sticky adhesive and covered with trapped flies inside a kitchen. The second shows it after being used outdoors, hanging upside down.

The poster explained that they live on a 10-acre property in a swampy area on the U.S. East Coast, where deer flies regularly swarm during the warmer months. "I would get absolutely obliterated by deer flies in the summer while walking my dog," the user wrote. They added that their pet had to remain on a leash because she "[committs] bird murder" otherwise.

After getting advice on a farming forum, the Redditor built a wearable version of a commonly made deer fly trap. But instead of attaching a blue, sticky bucket to a moving tractor, the traditional method — they mounted the bucket on their own head. "I stopped getting bit/dive bombed by these flies," they wrote. "Not a SINGLE one went for my body proper. They ALL target this thing."

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According to the post, after wearing the device for several weeks while spending two to three hours outdoors each day, the number of flies caught gradually declined. The Redditor was unsure whether that decline reflected the insects' natural life cycle or an actual reduction in the local population caused by the trap.

The post prompted many users to share their own encounters with biting flies. One asked whether deer flies were simply another name for horse flies. "Nope, deer flies are their own special brand of swamp pest, unfortunately," the original poster replied. "I actually prefer horse flies… Deer flies are smaller and IMO more aggressive."

Other users offered variations of the idea. One suggested freezing water inside a blue plastic cup and attaching replaceable flypaper to its sides instead of repeatedly coating a container with adhesive. Another explained that the sticky substance used in the trap, Tanglefoot, is an adhesive typically applied to tree trunks or garden surfaces to trap insects.

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Redditors discuss the DIY fly trap.

Several users cited research that supports the trap's design. One brought up a 2023 study published in the Proceedings of the Royal Society, which found that many biting flies are drawn to blue objects due to how their eyes process color.

Others recommended alternatives like blue hard hats, commercial "Bug Balls," TredNot patches, and even decorative dragonflies designed to discourage biting insects.

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