科学美国人60秒:For Halloween, Consider the Chocolate Midge

As you unwrap a Halloween candy or two, it's worth paying your respects to the real reason for many of the treats: a tiny fly whose trick is to make chocolate possible.  

"They're all in the family Ceratopogonidae, which is the biting midges family. But not all of the adults bite. How we usually do it is we call them 'Cerats.'" Erica McAlister is a fly scientist at the Natural History Museum of London, and author of The Secret Life of Flies. 

The "cerats"—related to no-see-ums—do a job that's very hard to get done by hand: they crawl through long, twisty cacao flowers, pollinating the stubborn cacao tree. Which produces the beans used to make chocolate. 

"They are really, really difficult to pollinate. So you do need these little things to do it."

And to McAlister, at least, the tiny midges are a beautiful sight to behold. "They look like a very tiny mosquito, but they are basically absolutely covered in hair, they're very beautiful, very hirsute little organisms. And the males have got the most—they look like feather duster antennae. He's got to not only smell for the female, he's listening. And his ears are on the antennae. They're not very robust, these things, they're tiny, as the name implies. They've got nice external genitalia for the boys… I don't know what else you want me to say <laughs>" 

Well, here's the bad news: The chocolate midges are in danger, as farmers clear out shade-grown rainforest plots, in favor of sunnier monocultures of cacao. That threatens the tiny flies, which need the damp rotting leaf litter of the forest floor to thrive. But some producers are taking notice. 

"Obviously our human demand for chocolate has gone up, so now a lot more research is going into fly pollinators, including these as well."

As for McAlister? She won't be joining you on that chocolate binge. "I can't stand it. Revolting stuff."

—Christopher Intagliata 

[The above text is a transcript of this podcast.]