Fairyflies such as our species Anagrus ustulatus , despite their name, are actually very tiny wasps, and can be found throughout the world. They average only 0.5 to 1.0 mm long and they include the world's smallest known insect, the Alaptus fairyfly, with a body length of only 0.139 mm, and the smallest known flying insect, at only 0.15 mm long.
While many insects form complicated social groups - think of ants and bees, for example - the fairyfly is just the opposite. Although they get together for mating, there's no courtship and no family groups among fairyflies. This makes them relatively hard to study, which is why much of their behavior is still a mystery to scientists.
Fairyflies are some of the most common chalcid wasps, but are rarely noticed by humans because of their extremely small sizes. This apparent invisibility, their delicate bodies, and their hair-fringed wings have earned them their common name. Their adult lifespans are very short, usually lasting for only a few 10 days. All known fairyflies are parasitoids of the eggs of other insects, and several species have been successfully used as biological pest control agents