By: Jennifer Welsh, LiveScience Staff Writer
Published: 07/02/2012 10:42 AM EDT on LiveScience

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.

Thailand's tiny fly

smallest fly

A reconstruction of the world's smallest fly, Euryplatea Nanaknihali, on the left is compared in size to an average house 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.

Follow Jennifer Welsh on Twitter @microbelover or LiveScience @livescience. We're also on Facebook & Google+.

Copyright 2012 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Also on HuffPost:

BIGGEST, FASTEST, DEADLIEST: EXTREME ANIMALS
Loading Slideshow...
  • Strongest Animal

    The Atlas beetle (pictured) can push around 850 times its weight.

  • Largest Invertebrate (Land)

    The coconut crab weighs about 6.6 pounds and its legs can span up to two and a half feet Liz Hall from the Melbourne Aquarium inspects Coconut Crab as he takes possesion of a coconut in Melbourne, 19 December 2006. They Coconut crab (also known as the Robber Crab) are the largest living crab in the world and can climb coconut trees to harvest coconuts which they can break with their huge nippers and have been gruesomely know to feed on injured or unconcious people in the bush. (William West, AFP / Getty Images)

  • The giant squid is the world's largest invertebrate, and the largest ever measured was 59 feet long. Giant squids also have the largest eyes of any animal, each one about the size of a human head.

  • Smallest Mammal

    The etruscan shrew is the smallest mammal (by weight) in the world. The smallest animal by skull size is the bumblebee bat.

  • Most Venomous Animal

    The sea wasp jellyfish (pictured) has enough venom to kill 60 adult humans. Photo: <a href="http://www.flickr.com/people/65578066@N00" target="_hplink">Guido Gautsch/Flickr</a>

  • Longest Migration

    Arctic terns migrate about 11,000 miles to the Antarctic each year...and then come all the way back! An Arctic Tern dives down to protect its nest on June 24, 2011 on Inner Farne, England. (Dan Kitwood, Getty Images)

  • Loudest Animal

    Blue whales' low-frequency pulses can be heard over 500 miles way. At 188 decibels, these sounds are louder than a jet engine. In this picture taken on March 26, 2009, shows a blue whale swimming in the deep waters off the southern Sri Lankan town of Mirissa. (Ishara S. Kodikara, AFP / Getty Images)

  • World's Most Extreme Animals

    North African ostriches run up to 45 miles an hour, making them the fastest land bird. They are also the biggest, weighing up to 345 pounds. An african ostrich eats at the Addo National Elephant Park, north of Port Elizabeth, on June 24, 2010. South Africa is hosting the 2010 FIFA World Cup. (Patrick Hertzog, AFP / Getty Images)

  • Fastest Bird

    Peregrine falcons dive toward their prey at over 200 mph. A young male Peregrine Falcon eats meat taken from the protective glove of Taronga Zoo bird trainer Erin Stone (unseen) following a short flying lesson in Sydney on December 9, 2009. (Greg Wood, AFP / Getty Images)

  • Fastest Fish

    Sailfish can swim at speeds of up to 68 mph, although experts disagree as to just which species of sailfish is the fastest. Sailfish jumping out of the water on January 16, 2006 in the Florida Keys, Florida. (Ronald C. Modra, Sports Imagery / Getty Images)

  • Fastest Mammal

    Cheetahs can run at speeds up to 70 mph. Majani, a 2-year-old male African cheetah, exhibits lighting speed Friday, March 19, 2004 while chasing a mechanical rabbit at the San Diego Zoo's Wild Animal Park as part of the Park's environmental enrichment program. (Ken Bohn, San Diego Zoo / AP)

  • Longest Lifespan

    Three giant tortoises are estimated to have lived over 175 years, with one estimated at a whopping 255 years. Image: Harriet, who died in 2006, was thought to be the third longest-lived tortoise on record. <a href="http://www.flickr.com/photos/doctorow/123660557/" target="_hplink">Cory Doctorow/Creative Commons</a>

  • World's Most Extreme Animals

    African elephants are the heaviest and second tallest land animals. Large males can exceed 13,000 pounds and are 12 feet tall at the shoulder. This photo made on February 10, 2011 shows an elephant in Tsavo west national park, some 350 kilometres southeast of Nairobi. (Tony Karumba, AFP / Getty Images)