Ichneumonidae

Definition

A family of parasitoid wasps in the superfamily Ichneumonoidea, order Hymenoptera, characterized by extremely high species diversity (~25,000 described, likely >100,000 total), slender bodies with elongate multi-segmented antennae, and larvae that develop as koinobiont or idiobiont parasitoids on immature stages of holometabolous insects and spiders. Females typically possess a conspicuous, often very long ovipositor used to deposit eggs into concealed hosts. Ichneumonids function as major regulators of arthropod populations in terrestrial ecosystems and are frequently employed in classical and augmentative biological control programs.

Etymology

From Greek ichneumon ('tracker') + Latin -idae (family suffix), referring to the female's host-searching behavior.

Example

The giant ichneumon Megarhyssa atrata uses its 10 cm ovipositor to drill into wood and parasitize larvae of the pigeon horntail (Tremex columba), a woodwasp; the developing wasp larva consumes the host from within, eventually killing it.

Synonyms

• ichneumon wasps
• ichneumonid wasps
• ichneumonids
• Darwin wasps

Related Terms

• Parasitoid
• koinobiont
• idiobiont
• ovipositor
• Braconidae
• Ichneumonoidea
• Biological control
• holometabolous

Usage Notes

Distinguished from the related family Braconidae by wing venation details, larval mandible structure, and molecular phylogenetics; historically grouped together as 'Ichneumonidae' sensu lato. The common name 'Darwin wasps' refers to Charles Darwin's famous letter expressing difficulty reconciling their parasitic life history with benevolent design.