What is "chalcid wasp"

n. Any of many parasitoid wasps of the superfamily Chalcidoidea

n. any of various tiny insects whose larvae are parasites on eggs and larvae of other insects; many are beneficial in destroying injurious insects [syn: chalcid fly, chalcidfly, chalcid]

Chalcid wasps (, , for their metallic colour) are insects within the superfamily Chalcidoidea, part of the order Hymenoptera. It is one of the largest insect families, with some 22,000 known species, and an estimated total diversity of more than 500,000 species, meaning the vast majority have yet to be discovered and described.

Most of the species are parasitoids of other insects, attacking the egg or larval stage of their host, though many other life cycles are known. These hosts are to be found in at least 12 different insect orders including Lepidoptera (butterflies and moths), Diptera (true flies), Coleoptera (beetles), Hemiptera (true bugs), and other Hymenoptera, as well as two orders of Arachnida, and even one family of nematodes.

A few species are phytophagous and the larvae feed inside seeds, stems, and galls. Generally beneficial to humans as a group, chalcids keep various crop pests under control, and many species have been imported to control insect pests. Copidosoma floridanum serves as a useful example of a wasp that provides pest control, and most recently, the wasp's genome is being sequenced by the Human Genome Sequencing Center as part of the i5K project, which aims to sequence the genomes of 5,000 arthropods.

They can be found almost everywhere, particularly on flowers, foliage, and in leaf litter, but are often overlooked due to their very small size, which includes the smallest of all known insects ( Dicopomorpha echmepterygis). Most larvae are parasites of other insects, if not hyper-parasites. A few are plant-feeders (such as Eurytomidae and Agaonidae).

Chalcids are tiny, dark-coloured wasps, often metallic blue or green with complex sculpturing on the body. They are also recognized by the characteristic reduced wing venation, similar to that seen in other superfamilies of parasitic wasps.