What shared anatomy defines insects in Order Hymenoptera?

Chewing mouthparts and forewings larger than hindwings.

The defining physical characteristics examined by scientists for the Order Hymenoptera include specific features related to feeding and flight structures. Insects belonging to this order must possess chewing mouthparts, which contrasts with insects possessing siphoning or lapping mouthparts found in other orders. Additionally, a key diagnostic feature is their wing structure: they have two pairs of membranous wings, and crucially, the anterior pair (forewings) must be noticeably larger than the posterior pair (hindwings). While many members, like wasps, possess stingers, this feature is not universal across the entire order, as sawflies (Symphyta) are included but lack this modification. Furthermore, while sociality is common, the order also encompasses solitary insects like many sawflies, meaning social structure is not a mandatory defining trait for the entire Hymenoptera grouping.