Planet Earth

Bees That Drink Sweat From People's Skin and Tears From People's Eyes

80beatsBy Sarah ZhangMay 1, 2012 11:12 AM
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Have you ever thought about how nutritious your bodily fluids are? Full of goodies like salts and proteins…Wild bees know all about it, feeding human sweat and tears as a source of nutrition.

Urban sweat bees, for example, use humans like a salt lick. “These bees prefer sweaty people—over most animals—because the human diet usually is so salty that their perspiration is saturated with the essential nutrient,” according to a recent feature in the Wall Street Journal on sweat bees. A new species (Lasioglossum gotham) of these bees was recently identified from a specimen netted in the heart of Brooklyn. Although they are as a group fairly common, they’re tiny and they don’t sting, which is why you probably haven’t heard New Yorkers complaining about them. “[M]ost people never notice when the tiny bees alight on a bare arm or leg,” says the WSJ.

But what about a bee in your eye, you’d probably notice that right? Scientists have investigated different families of bees in Thailand that drink tears, both human and animal. Eyes wide open, the researchers used themselves as bee bait. (They also used meat, Ovaltine, cheese, and other foods but the bees preferred human tears.) These bees were persistent too:

On landing, automatic blinking with the eye often prevented the bee from getting a firm hold, causing it to fall off the eyelashes. If so, the bee persistently tried again and again until it was successful, or finally gave up and flew off. In a very few cases the approach was so gentle that the host (H.B.) did not realize he had a Lisotrigona attached to his lid, imbibing his tears. After landing and whilst sucking tears, H.B. often could barely feel the presence of a bee; indeed, checking by mirror was then required to make sure whether it was still there or had left.

However, when several bees were involved, the experience was rather unpleasant, causing strong tear flow. Once a bee had settled and more were approaching, these tended to settle near each other in a row. Closing the eye did not necessarily dislodge bees but some continued to suck at the slit. They were even able to find and settle at closed eyes.

The researchers eventually captured 262 of these tear-drinking bees using their own eyes as bait. They hypothesize that the bees use human tears as a primarily as a protein source, though the salt may be part of the appeal too. Next time you’re wiping off sweat or tears, remember there are starving bees somewhere who would love to drink some of that stuff.

Image courtesy of Hans Bänziger / Journal of the Kansas Entomological Society

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