This might surprise you: flies often land on humans not because of dirt, but because of salt.
When sweat evaporates, it leaves tiny crystals of salt on your skin. Many types of flies rely on minerals like sodium, and your skin becomes an easy source.
This explains why flies sometimes land on:
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arms
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legs
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neck
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face
They’re not trying to annoy you—they’re looking for minerals.
7. Movement Attracts Flies Instantly
If you move your hands a lot, walk quickly, or sit in a windy area, flies will notice. Movement signals energy and heat—two things flies are programmed to follow.
Even waving your hands to chase them away can sometimes make them more curious.
This is why runners, outdoor workers, and active people tend to be chased more.
8. Heat: Flies Can Sense It From a Distance
Flies have tiny sensors that detect temperature changes around them. Humans radiate heat naturally, especially from:
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the head
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neck
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armpits
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chest
Warm spots attract flies, which is why they hover around your face or upper body.
The warmer the day, the more likely this behavior becomes.
