An almost microscopic fly no bigger than a grain of salt has just been discovered by scientists in Thailand. The tiny winged insect, Euryplatea nanaknihali, belongs to a group of hump-backed flies that have a nasty way of propagating: When they're about to lay eggs they seek out enemy ants, parasitically lay their eggs inside them, and wait for newly-hatched larvae to burrow their way out of the dying ant's brain. Here, a concise guide:

How big is the fly?
It's really, really tiny. The fly is about five times smaller than a fruit fly at 0.4 millimeters in length, and is capable of resting comfortably on the eyeball of a normal-sized fly. "It's so small you can barely see it with the naked eye on a microscope slide," says lead researcher Brian Brown, who identified the fly as a new species in the July issue of the journal Annals of the Entomological Society of America. "The housefly looks like a Godzilla fly beside it."

Is it the smallest bug on record?
Not even close. A number of other insects, especially wasps, are microscopic on the cellular level. The fairy wasp, for example, is just 0.14 millimeters in length, or "about the size of a human egg cell," says Jennifer Welsh at LiveScience

And this fly eats the brains of ants?
Though this tiny critter hasn't actually been caught in the act (yet), it has parasitic habits similar to 4,000 other known species of phorid flies that feast on ant brains. It's a really "gruesome" practice, says Ed Yong at Discover Magazine. After laying eggs inside their victims, the maggots hatch, eat their way towards the ant's head, and gorge upon its brain and other tissues. "The ant stumbles around in a literally mindless stupor until the connection between its head and body is dissolved" by a special enzyme. Then, the head falls off "and the adult flies burst out."

What does discovering this fly mean?
Scientists believed that over time the C. rogenhoferi ant in Thailand developed a smaller body to ward off brain-eating flies — if your head's too small to lay eggs in, why would the flies bother? This new discovery "goes to show that there is no way of truly escaping from parasites," says Yong. "If you evolve a minuscule body, they will shrink even further in pursuit." 

Sources: Discover Magazine, io9 , LiveScience