Odonata

Definition

An order of predatory, hemimetabolous insects comprising the dragonflies and damselflies. Adults possess large compound eyes, two pairs of elongate, membranous wings with complex net-like venation, and a robust, elongate abdomen; they are agile aerial predators that capture prey on the wing but rarely walk. Larvae (naiads) are aquatic, with modified labia forming a prehensile 'mask' for ambushing prey. The order is traditionally divided into two major subgroups: Anisoptera (dragonflies), with hindwings broader than forewings, eyes contiguous or nearly so, and wings held horizontally at rest; and Zygoptera (damselflies), with wings of similar shape, eyes widely separated, and wings folded together above the body at rest.

Etymology

New Latin, from Ancient Greek ὀδούς (odoús, 'tooth'), referring to the toothed mandibles characteristic of the group

Example

The Common Blue Damselfly (Enallagma cyathigerum) and the Broad-bodied Chaser (Libellula depressa) represent the two major odonate lineages: at rest, the damselfly folds its wings together above its slender abdomen, while the dragonfly holds its wings spread flat like an airplane.

Related Terms

• Anisoptera
• Zygoptera
• Epiprocta
• Palaeoptera
• hemimetabolous
• naiad
• Direct flight muscles
• quadrilateral
• pterostigma
• labial mask

Usage Notes

Specialists distinguish dragonflies (Anisoptera) from damselflies (Zygoptera) by wing shape, eye position, and resting posture; the term 'dragonfly' is sometimes used loosely for the entire order, but this is taxonomically imprecise. The subordinal classification has been revised in recent phylogenetic treatments, with some authorities recognizing Epiprocta (dragonflies plus the relict family Epiophlebiidae) as sister to Zygoptera. Odonata is placed in the infraclass Palaeoptera, characterized by wings that cannot be folded flat over the abdomen—a trait shared with mayflies (Ephemeroptera) but not with any other living insect order.