Just when you thought parasitic insects couldn’t get more gross…
The entomology geeks and nerdlings over at LiveScience.com give us more fodder for our nightmares!
In a recent article, LiveScience staff writer Jennifer Welsh reports that 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.
Picked up by the Thailand Inventory Group for Entomological Research in Kaeng Krachan National Park, the tiny fly is the first of its kind discovered in Asia. The researchers named the new fly Euryplatea nanaknihali.
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.
I don’t know about you but I have enough nightmare material to last me the whole weekend!
 While this is the world’s smallest fly, it is by no means the world’s 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