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.
Bee
Behaviourally, one of the most obvious characteristics of bees is that they collect pollen to provide provisions for their young, and have the necessary adaptations to do this. However, certain wasp species such as pollen wasps have similar behaviours, and a few species of bee scavenge from carcases to feed their offspring. The world's largest species of bee is thought to be the Indonesian resin bee "Megachile pluto", whose females can attain a length of . The smallest species may be dwarf stingless bees in the tribe Meliponini whose workers are less than in length.
A bee has a pair of large compound eyes which cover much of the surface of the head. Between and above these are three small simple eyes (ocelli) which provide information for the bee on light intensity. The antennae usually have thirteen segments in males and twelve in females and are geniculate, having an elbow joint part way along. They house large numbers of sense organs that can detect touch (mechanoreceptors), smell and taste, and small, hairlike mechanoreceptors that can detect air movement so as to "hear" sounds. The mouthparts are adapted for both chewing and sucking by having both a pair of mandibles and a long proboscis for sucking up nectar.