This Freaky Fruit Fly Lays Eggs in Your Strawberries

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The spotted wing drosophila may look like a common fruit fly, but it's so much worse. Just as strawberries, blueberries, raspberries and blackberries are ripening in the field, this fly saws into them and lays her eggs inside. The growing maggots turn the fruit into a mushy mess. Could a wasp and its own hungry maggots save the day?

TRANSCRIPT

You’ll never delight in this juicy raspberry, if this fly gets its way. It’s called a spotted wing drosophila because the male has dark spots on its wings.

Common fruit flies are maddening enough, crawling around and feeding on your overripe bananas.

Their spotted wing cousins are way worse. They ruin blueberries, raspberries, blackberries and strawberries at their mouth-watering prime, before they can ever reach your kitchen.

Out in the strawberry patch, this female spotted wing drosophila is ready to lay some eggs. She uses this tool, called an ovipositor, to cut into the fruit.

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Her ovipositor is long and has two rows of teeth. Much more impressive than the common fruit fly, which uses a smaller, smoother ovipositor to lay eggs on rotting fruit.

The spotted wing drosophila uses the extra cutting power to dig a hole into firm fruit while it’s still in the field. Then she pushes her egg in.

See that tiny white string she left behind? It looks like one of the strawberry hairs, but that’s how the egg will breathe. Kind of like a snorkel.

Within three days the egg hatches into a squirmy maggot. It makes itself at home – in this case, in a blueberry. The maggot transforms into a pupa at the fruit’s surface, where it breathes through two star-shaped tubes called spiracles. All this mucking about in the pulp ruins the fruit, so it never makes it to market.

These flies cost farmers millions all around the world. They’re originally from East Asia. Growers have to spray insecticides to kill them.

That’s why scientists are introducing a less toxic option. They’ve invited an old enemy from Asia to take the fly down.

This parasitic wasp is even tinier than the fly, but just as determined to lay her eggs. Her favorite spot is inside a fly’s growing maggot. She can feel vibrations that lead her to a fly maggot moving below the fruit’s surface.

She slides a thin needle into the blueberry and injects an egg straight into a maggot. The wasp egg hatches. But instead of killing the fly maggot right away, it waits for it to plump up and develop a hard casing. Then the wasp maggot devours the fly and grows into an adult.

All that’s left of the fly is its casing, from which the triumphant wasp emerges. It’s a boy! You can tell by the long antennae.

Scientists have been raising these wasps in labs in the U.S. Soon they’ll be released into fields across the country. Based on their research, scientists say the wasps will almost exclusively target spotted wing drosophila and the occasional common fruit fly.

The wasps can cut down the number of flies, but only up to about half. So, farmers will still need to use some pesticides. They’ll be playing a game of whack-a-mole to prevent flies from turning our scrumptious berries into mush.

Hey, Deep Peeps! If you liked seeing the spotted wing drosophila meet its match, we have an episode about the gruesome death of fruit flies. Watch how a killer fungus turns them into spore-launching zombies. Enjoy!