Metamorphosis is complete, and the larvae are usually without legs. Pupae are usually in a cocoon. Parthenogenesis is frequent, in some cases giving rise only to males but in others producing females as well. Suborder Symphyta consists of the more primitive hymenopterans. The waist is not present and the ovipositor is adapted for sawing or boring.
Parasitism is rare.
Suborder Apocrita contains the majority of Hymenoptera with the typical 'waisted' appearance. There are a large number of parasitic families, all with the ovipositor adapted for piercing. Several families produce galls on plants. The Cynipidae, for instance, produce the familiar oak galls and also those on roses. Most are parasitic on other insect eggs, larvae, or pupae, and several are used for biological control of pests.