Chalcidid Wasps

In 1923 Gahan and Fagan (U. S. Natl. Mus., Bul. 124: 24, 31, 133) changed the application of the well-known names Chalcis, Brachymeria, Smicra and Smiera. These names had been used extensively in the literature for almost a century. The changes very well may have been erroneous, because of the fact that Gahan and Fagan had examined none of the types of the type-species involved. Their conclusions were based entirely on a study of the literature, principally volume 5 of Dalla Torre's Catalogus Hymenopterorum, published in 1898. That work was a bibliographic, not a taxonomic, one. However, these changes in the application of familiar names were accepted by all subsequent workers except for Schmitz, who published a large work on the Ethiopian Chalcididae in 1946. All other works in the world literature followed Gahan and Fagan. An enormous literature that used these names as redefined by Gahan and Fagan has been published in the last 50 years. It would be a mistake at this late date to try to reverse the changes made by Gahan and Fagan, irrespective of their soundness. It should be kept in mind, however, that the application of those names before and after 1923 is quite different.

Members of the genus Dirhinus have been reared numerous times from tephritid puparia. The species of this genus burrow through the substrate to locate puparia. Oviposition is through the puparial wall onto the host pupa (Silvestri 1914). Silvestri (1914) brought Dirhinus giffardii (Silvestri) from Africa to Hawaii, where it was propagated, released, and became established on medfly, Ceratitis capitata. Later (1971), this species was introduced as a biological control agent in Bolivia against medfly (Bennett and Squire 1972).

The species of Dirhinus can be readily recognized by the fact that the antennae are inserted in a deep concavity formed by two ridges extending out from the face (Figs. 1-3). In dorsal view, these appear as two horn-like protruberances.

Species in the genus Conura are also occasionally reared from fruit-infesting tephritids, but only rarely.

For additional information, see the Dirhinus and Dirhinus giffardii pages.

Chalcid wasps (Chalcididae) are mainly parasitoids, meaning their larvae are parasites that eventually kill their hosts. They are found worldwide, although they are predominantly tropical. Chalcid wasps are small, about 6 mm in length. They range in color from black, with white or yellow marks, to yellow. They are robust with enlarged hind legs, and a flat forewing. Chalcid wasps are predominantly solitary, although a few species may be gregarious. These parasitoids most often attack pupae of moths, butterflies (Lepidoptera), and flies (Diptera), but occasionally sawflies, wasps, bees, ants (Hymenoptera), and beetles (Coleoptera). Females lay up to 200 eggs. These eggs are deposited into fully grown hosts, like mature larvae, or young pupae. Eggs pupate and feed and grow inside the host pupa. Most chalcid wasps then overwinter as adult females or as mature larvae in the host organism. Although chalcid wasps are not known for their pollination services, studies have documented various species of chalcid wasps visiting flowers and perhaps contributing to pollination of the plants. Plants visited include acacias (Acacia spp.) by chalcid wasps in the Hockeria genus, kudzu (Pueraria montana) by Conura amoena, Sacramento burbark (Triumfetta semitriloba), and mango (Mangifera indica).

The Chalcididae are a moderate-sized family within the Chalcidoidea, composed mostly of parasitoids and a few hyperparasitoids. The family is apparently polyphyletic, though the different subfamilies may each be monophyletic, and some may be elevated to family status in the near future. As presently defined, there are over 85 genera and over 1460 species worldwide. They are often black with yellow, red, or white markings, rarely brilliantly metallic, with a robust mesosoma and very strong sculpturing. The hind femora are often greatly enlarged, with a row of teeth or serrations along the lower margin.

One of the more remarkable uses of the muscular hind legs is the species Lasiochalcidia igiliensis, which attacks the predatory larvae of ant lions, holding the mandibles of the larva spread apart while the wasp injects an egg into the membrane of the exposed throat.