Some male butterflies drink beer as part of a nutrient-rich package they provide to females.
Katy Prudic, an entomologist at the University of Arizona: “I’ve gotten butterflies out of beer cans before."
Males likely drink beer to boost their spermatophores, nutrient-rich packages that they give to females as a nuptial gift, Prudic says.
It's not just butterflies: Many entomologists often bait insect traps with beer. If they run out, no worries—a nice pinot will do just as well.
A 2008 study found that 35 species of moths were just as attracted to traps baited with wine as with beer.
Some male butterflies drink beer as part of a nutrient-rich package they provide to females. [Photo by Tim Laman]
Other insects turn to drink when they’re sexually rejected.
In a 2012 study in the journal Science, researchers compared the diet preferences of male fruit flies that had successfully mated with those of males that had not mated.
The results showed that unmated males preferred food-containing alcohol, while the mated males did not.
Further study showed that mated males had higher levels of a brain chemical called neuropeptide F, which may spike when the fly receives a reward—like sex.
Male fruit flies that don't have sex turn to alcohol to reward themselves, research shows. [Photo by Scott Camazinehan]
Unmated mates had lower levels of neuropeptide F, which is likely why they turned to alcohol to boost their feeling of satisfaction.
Supporting this theory, unmated male fruit flies given artificial doses of neuropeptide F avoided alcohol.
Some mammals also accidentally get drunk—usually from nectar or fermented fruit.
Male fruit flies that don't have sex turn to alcohol to reward themselves, research shows.
Don Moore, associate director of the Smithsonian National Zoo in Washington, D.C., says via email that he’s observed the effect of overripe fruits on animals firsthand.
“I’ve watched white-tailed deer eating fermented apples in orchards," Moore says. They get pretty “sleepy,” even “stumble-y.” It’s a common observation in apple-growing regions, he adds.
In 2011, various news outlets reported on an intoxicated moose that got stuck in an apple tree in Sweden.
This video allegedly shows a squirrel that hit the fermented crabapple sauce, though Moore thinks it's more likely the animal was injured.
Other animals have a higher tolerance for fermented treats. Malaysia's pen-tailed tree shrew eats nectar from the flowers of the betram palm, which has one of the highest alcohol levels recorded in a natural food—3.8 percent, according to a 2008 study in the Proceedings of the National Academy of Sciences.
These shrews can really hold their nectar: Despite boozing nightly on the high-alcohol nectar, they show no effects of intoxication.
Many bats that eat fermented fruits and nectar are also fine to fly. A 2010 study in the journal PLOS ONE found that flight and echolocation skills of New World leaf-nosed bats were unaffected by their consumption of ethanol.
But leave the drinking and flying to them. You’d be bats to try it yourself.