Wasp
The largest social wasp is the Asian giant hornet, at up to in length. The various tarantula hawk wasps are of a similar size and can overpower a spider many times its own weight, and move it to its burrow, with a sting that is excruciatingly painful to humans. The solitary giant scoliid, "Megascolia procer", with a wingspan of 11.5 cm, has subspecies in Sumatra and Java; it is a parasitoid of the Atlas beetle "Chalcosoma atlas". The female giant ichneumon wasp "Megarhyssa macrurus" is long including its very long but slender ovipositor which is used for boring into wood and inserting eggs. The smallest wasps are solitary chalcid wasps in the family Mymaridae, including the world's smallest known insect, "Dicopomorpha echmepterygis" (139 micrometres long) and "Kikiki huna" with a body length of only 158 micrometres, the smallest known flying insect.
Trichogramma
Although several groups of egg parasitoids are commonly employed for biological control throughout the world, "Trichogramma" spp. have been the most extensively studied. More than a thousand papers have been published on "Trichogramma" species, and they are the most used biological control agents in the world. "Trichogramma" spp. are unique in approaching the size limit of how small an insect can be, which would be determined by how few neurons they can fit in their central nervous systems, yet exhibiting a complex behavior to sustain their lives. These wasps have less than 10,000 neurons, which is 1/100th that of the next smallest insect.