A Tsetse Fly Births One Enormous Milk-Fed Baby | Deep Look
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A Tsetse Fly Births One Enormous Milk-Fed Baby | Deep Look


We mammals like to think we’re pretty special,
right? We don’t lay eggs. We feed our babies milk. Well, this very pregnant fly is about to prove
us wrong. Yep, this tsetse fly is in labor. And that emerging bundle of joy is her larva. While other insects can lay hundreds of eggs,
she grows one baby at a time inside her, just like us. Congratulations! Scientists think tsetse flies started growing
their young like this long ago to guard them from parasites. For that same reason, the larva doesn’t
stick around. It burrows into the dirt for protection. It’s already gotten all the nutrition it
needs from its mom’s milk. That’s right, this fly makes milk. Here’s a drop of it under the microscope. It’s made up of protein and fat, a lot like
breast milk. The fly doesn’t exactly breastfeed, though. Inside its mom, the larva got milk through
these tubes … which it drank with this pair of straw-like mouthparts on its head. A female tsetse fly needs a lot of fuel, because
over her 10-day pregnancy she produces her own body weight in milk. And that fuel comes from us. Tsetses feed exclusively on blood … from
humans and other animals. That’s bad news because where the flies
live in Africa they spread a debilitating disease called sleeping sickness in humans
and nagana in livestock. Tsetses make cattle so sick that they can’t
be raised efficiently in a region of Africa the size of the United States. Geoff Attardo (off-camera): All right. Coming back to the first trap we set. People are trying to control them with things
like baited traps. Geoff Attardo (off-camera): It looks like
it has a lot of tsetse flies. Man (off-camera): Tsetse. Geoff Attardo (off-camera): Holy cow! That’s a lot of flies. Man (off-camera): Tsetse flies. They’re effective, but more defenses are
needed. That’s where Geoff Attardo, at the University
of California, Davis, hopes to help. He’s trying to stop tsetse flies from making
babies in the first place. A female only mates once in her life, enough
to make the 10 or so babies she’ll have. The male makes sure she doesn’t mate again
by delivering a substance that makes her lose interest in sex. Scientists are trying to figure out what it
is. If they could bottle it and spray it, female
tsetse flies may never get busy at all. No more tsetse offspring to worry about. After spending about a month below ground
in a hard shell, the fly emerges as an adult and unfurls its wings. Like us, tsetse flies ensure the next generation
by investing a lot in a few offspring, instead of investing very little in a lot of them. They grow up so fast, don’t they? Hi, it’s Lauren. We have a few other episodes about insect
moms. Blue orchard bees build nests that look like
stunning jewels. And gall wasps trick trees into making their
young a glitzy mansion. See you next time!

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