Hymenopterans

Hymenoptera is a diverse order of insects that includes sawflies, wasps, bees, and ants. Described species number in the tens of thousands, with many more likely undiscovered, and members occupy nearly every habitat on Earth. The order consists of two groups: Symphyta (sawflies) and Apocrita (stinging wasps, bees, and ants).

Most hymenopterans have two pairs of membranous wings; hind wings are often coupled to the fore wings by hamuli. Adults and larvae undergo complete metamorphosis (egg, larva, pupa, adult). Mouthparts are typically adapted for chewing, piercing, or nectar feeding. The female usually has an ovipositor, which in many species can be modified into a sting.

Ecology and behavior: Many species are parasitoids whose larvae develop inside or on other insects, notably in families such as Ichneumonidae and Braconidae. Others are predators or herbivores. Hymenoptera include important pollinators (especially bees) and numerous natural enemies used in biological control. Several groups are eusocial, forming colonies with cooperative brood care, division of labor, and overlapping generations; best known are ants (Formicidae), honeybees (Apoidea/Apidae), and some paper wasps (Vespidae).

Taxonomy and diversity: Within Apocrita, ants, bees, and most wasps are highly diverse, with groups such as Chalcidoidea (parasitic wasps), Ichneumonoidea, Vespoidea, and Apoidea. Sawflies (Symphyta) lack a narrowed waist between the thorax and abdomen, a trait distinguishing them from Apocrita. Hymenoptera are cosmopolitan, ranging from tiny parasitoids to large stinging insects and social bees.