Monday, July 21, 2014

Why Do Butterflies Drink Water?

It was a Sunday yesterday, and out of the curiosity to test the macro feature on my camera lens I figured I'd pay a visit to the Kuala Lumpur Butterfly Park. The park is located near the Kuala Lumpur Bird Park, and the entrance fee is only RM 10 for Malaysian, but RM 20 for foreign visitors.

While shooting pictures of the critters I noticed something strange: the butterflies intermittently danced around and landed on the wet floor.
Are they drinking water?
But why?

Butterflies drink nectar from flowers (and whatever that is sweet). I've seen butterflies landing on peeled pineapples and apples to suck on the sweet juice, and all these sweetness contains liquid. So they're essentially eating and drinking at the same time. And since they're getting liquid from nectar, why do they have to drink water? Animals like camels and caterpillars obtain liquid from the plant they consume, so they never have to drink water at all.   
Landing is a risky business for butterflies. There's always the danger of predation out in the open and, in the butterfly park yesterday, some poor insects inadvertently had their massive wings touched the wet ground and got stuck. Therefore it's rare for them to land on a particular plant for anything more than a few seconds (unless when the temperature drops eg. at night or cloudy day, the insect-- being cold blooded --becomes inactive. Even then they would hide under leaves or camouflage themselves on twigs, but never out in the open). So why would butterflies exposed themselves to so much risk to drink water?
It turns out that the butterflies are not going after the water; they are going after something in the water. 
Nectar is a brew of many chemicals: amino acids, glucose, fructose and sucrose. Some nectars even contain neurotoxins and nicotine. But nectar contains very little salt, and butterflies need salt for egg production and metabolism, and that's the reason why butterflies set out to acquire salt by other means.

To scavenge the precious mineral, butterflies look for river, sweat (sometimes butterfly lands on you? Bravo~), carrion, faeces, urine, blood and even tears. After absorbing the salt, the insect would excrete the excess water from its system. This reminds me of an incident I encountered back in 2012 on Redang Island: I was participating in the SEATRU program and on the second last day we saw a butterfly perching lifelessly in the front yard. It refused to take off even when agitated, and kept on ejecting water from its anus, which led us to think that it was peeing and couldn't fly.
National Geographic Newswatch posted an article last month explaining the phenomenon of butterflies and bees drinking crocodile tears, and it explains that the correct term for tear-drinking is lachryphagy. But the whole thing about acquiring minerals from water by butterfly is called mud-puddling.

So you get excited when a butterfly lands on you? ;)




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