Evaniidae

Common Name

Ensign Wasps

Overview

Evaniidae, commonly known as ensign wasps, consists of a family of parasitoid or parasitic wasps. They derive their name from the movement of their metasoma, which resembles a flag or ensign being waved.

Taxonomy

Key Characteristics

  • Appearance: Small to medium-sized wasps, usually 3-10 mm in length.
  • Metasoma: Highly distinctive stalked metasoma that looks like a small flag.
  • Antennae: 13-segmented in males and 12-segmented in females.
  • Wings: Well-developed with a characteristic venation pattern.

Life Cycle

Behavior and Ecology

Ensign wasps are principally known for their role as parasitoids of cockroach eggs. The adult females search for cockroach egg cases, lay their eggs within, and the resulting larvae consume the cockroach's eggs from within. This parasitic relationship helps to control cockroach populations in environments where both insects coexist.

Notable Species

  • Evania appendigaster: One of the most well-known species, widespread globally, and often used in biological control efforts against cockroaches.
  • Brachygaster minutus: Another species within the family, notable for its smaller size.

Conservation

Ensign wasps are not generally considered at risk. Their ecological role in controlling cockroach populations is beneficial, and they are often found in both urban and rural settings.

Significance to Humans

Ensign wasps are valuable in controlling pest cockroach populations, particularly in human-inhabited areas. Their presence is often welcomed as a natural form of pest management.

Fun Facts

  • Behavior: Ensign wasps get their name from the flag-like movement of their abdomen.
  • Diet: Adult ensign wasps usually feed on nectar or not at all, focusing instead on finding and parasitizing cockroach eggs.
  • Historical Mention: The first description of an ensign wasp dates back to Carl Linnaeus in 1758.
  • Diversity: Around 400 species of ensign wasps are currently recognized across the world.