The hymenopterans (sawflies, wasps, bees, and ants) are one of the largest of the insect orders, and may turn out to be the largest when also hitherto undescribed species are considered.

The hymenopterans demonstrate an enormous diversity in life styles, but the majority of the species are parasitoids on other arthropods. Among these is the smallest known flying insect, a fairy wasp measuring only 0,15 mm. The hymenopterans are most well known for the social species belonging to the stinging wasps (Aculeata), i.e. the ants, bees, bumblebees, hornets and other social wasps. The social hymenopterans form colonies consisting of female workers led by one or more queens. Social hymenopterans have many key roles in the ecosystem; ants and wasps are important predators, and bees and bumblebees play an enormously important role as pollinators both in nature and in agriculture.