Inna-Marie Strazhnik
A reconstruction of the tiny phorid fly Euryplatea nanaknihali (below), with its body size compared with a house fly (Musca domestica). This family of flies is known for laying eggs in living ants.
By
updated 7/2/2012 1:52:48 PM ET 2012-07-02T17:52:48

A new fly discovered in Thailand is the world's smallest. It is five times smaller than a fruit fly and tinier than a grain of salt (0.4 millimeters) in length — half the size of the smallest "no see-ums." It probably also feeds on tiny ants, likely decapitating them and using their head casings as its home.

"It's so small you can barely see it with the naked eye on a microscope slide. It's smaller than a flake of pepper," said Brian Brown, of the Natural History Museum of Los Angeles County, who identified the fly as a new species. "The housefly looks like a Godzilla fly beside it."

The tiny finding is detailed in the July 2012 issue of the journal Annals of the Entomological Society of America.

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Thailand's tiny fly
The type specimen, a female, was picked up by the Thailand Inventory Group for Entomological Research in Kaeng Krachan National Park. The fly is the first of its kind discovered in Asia. [ Microscopic Monsters: Gallery of Amazing Bugs ]

It has smoky gray wings and the female they discovered has an egg-depositing organ that is pointed to make it easy to lay eggs inside another insect, as a parasitic fly would. While it's not the smallest insect (that title belongs a species of fairy wasp, coming in at 0.14 millimeters in length, about the size of a human egg cell), it is the world's smallest fly.

"When you get really small like that, the environment changes," Brown said. "The viscosity of air starts to become a problem and wind currents are major events. It's amazing how small something can be and still have all of its organs. This is a new frontier, and publishing this tiny fly is basically a challenge to other people to find something smaller," he said.

Feeding on ants
The researchers named the new fly Euryplatea nanaknihali. It comes from a group of 4,000 hump-backed flies called phorid flies. One genus of the fly, Pseudacteon, is known for its anti-ant behaviors, which include decapitation. They usually range from 0.04 inches to 0.12 inches (1 millimeter to 3 millimeters) in length, so they can only prey on larger ants.

The flies lay their eggs in the body of the ant; the eggs develop and migrate to the ant's head where they feed on the huge muscles used to open and close the ant's mouthparts. They eventually devour the ant's brain as well, causing it to wander aimlessly for two weeks. The head then falls off after the fly larva dissolve the membrane that keeps it attached.

The fly then takes up residence in the decapitated ant head for another two weeks, before hatching out as a full-grown adult. In this case, researchers think the fly parasitizes tiny acrobat ants, whose heads are about as large as the fly itself and grow to about 0.16 inches (4 millimeters) long.

They haven't been able to see this in action, but think it's likely in the newfound fly since the fly's closest relative decapitates ants in Equatorial Guinea.

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© 2012 LiveScience.com. All rights reserved.

Explainer: Eight insects with the 'ick' factor

  • Warren Little  /  Getty Images file

    Many insects provide humans with unheralded services such as pollination, sustenance, and pest control, but some of them gross us out — or worse. Take dung beetles such as the one shown in this image, for example. As their name implies, the insects process feces for their livelihoods. The service helps reduce fertilizer costs on grazed agricultural lands and cuts down on the number of flies and parasites the piles of manure would otherwise attract. But a life of dung? Ick.

    Click the "Next" arrow above to learn about seven more insects with "ick" factors that make us squirm, or much worse.

    — By John Roach, msnbc.com contributor

  • Head lice, the annoying itch

    Sean Gallup  /  Getty Images file

    For moms and dads, the thought of head lice can sow panic at home. School-age kids are prone to pick up the feared infestation of the sesame-seed sized insects in packed classrooms. The critters latch onto hair follicles and feed on tiny drops of blood. At first sight of head lice, many school nurses send infected — and itchy — students straight home. And that's when parents freak out, lathering their kids with shampoos, gels and creams in an effort to kill the lice. However, some lice are proving resistant to the treatments, leaving parents scratching their heads over what to do.

  • Crabs, lice of another kind

    James Castner  /  University of Florida

    Adults, perhaps in the kid-making stage, are also panicked by another kind of lice: crabs. These critters nest in pubic hair and are often transmitted in the course of sexual intercourse. Crab-inspired panic attacks, however, might be on the way out. Researchers at the University of Leeds in Britain noted a decline in crab infestations, first among women and then men, reported at their clinic. The researchers speculated in the journal of Sexually Transmitted Infections that the decline is due to the popularity of the so-called Brazilian bikini wax, which removes most pubic hair, The Associated Press reported.

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    The adage about bedbugs is getting harder to follow, according to entomologists and pest control experts who have noted an uptick in infestations of the blood-sucking insects. Heavy use of insecticides such as DDT all but eradicated bedbugs from the U.S. by the late 1960s, but international travelers appear to have re-opened the door and now, media reports suggest, bedbugs are back with a vengeance. The insects attack warm bodies in the middle of the night and then retreat to dark crevices behind headboards and mattresses. Telltale signs of their presence include pepperlike fecal spots and shed skins.

  • Cockroaches have few fans

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    Garbage-loving, foul-smelling and house-infesting cockroaches have few admirers beyond Disney-Pixar's animated robot Wall-E, whose only friend on a post-apocalyptic Earth is, naturally, among the world's most enduring insects. The notoriously difficult-to-kill bugs can spread disease and cause allergies. Researchers are hoping baits that mimic the pheromones females give off when they are ready to mate can at least give humans an edge in the battle for pest-free environments. In this image, a female cockroach at upper right attracts three males with her scent.

  • Ticks can make people bug out

    AP file

    Ticks, although not technically insects (they're arachnids like spiders and mites), make some people bug out. The critters crawl onto hosts such as dogs and people and burrow in their heads to suck blood. Ticks can go undetected for days, ample time to spread sometimes fatal illnesses such as Lyme disease and Rocky Mountain spotted fever. Prevention requires application of insect repellant when outside and regular body checks for potential bites. If a tick is detected, experts advise not to panic, but to expeditiously remove the tick by grasping it with tweezers as close to the skin as possible and pulling upward with steady, even pressure. A brown dog tick is shown here.

  • Fleas no fun for Fido or his best friend

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    The "how cute" reaction evoked by scenes such as the one shown here can quickly change to "ick" when our dogs start gnawing on their fur to rid themselves of fleas. The wingless, blood-sucking insects can also be more than an itchy nuisance: they are known to spread bubonic plague between rodents and humans, which has killed millions of people. Experts recommend frequent vacuuming, regular washing of pet bedding and treating household pets with topical insecticides.

  • Mosquitoes the icky and deadly

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    For many of us, mosquitoes are more annoying than nasty; though most of us have uttered an ick or two when we successfully swat one on an exposed arm or leg only to create a skid mark of our own blood and bug. But more than ick, the insects are vectors of lethal disease. More than a million people each year die from malaria, a disease caused by parasites in red blood cells that is spread by mosquitoes in some parts of the world such as Africa. In an experiment with a twist, scientists attempting to develop a malaria vaccine recently successfully used mosquitoes to vaccinate humans against the disease.

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