This week’s wasp is the cockroach hunter wasp species Ampulex compressa, the emerald cockroach wasp! This species was first described by Johan Christian Fabricius in the year 1781, who originally placed it in the genus Sphex. The specimen photographed here was collected in Hawaii by W. W. Boyle, a previous manager of the Frost Entomological Museum. This species is native to the tropical regions of Africa, Asia, and the Pacific Islands. It was also introduced to Hawaii in 1941 as a means of biological control against cockroaches, although the effort has overall been deemed unsuccessful.

Taxonomy: This species is a member of the superfamily Apoidea and the family Ampulicidae. The superfamily Apoidea includes bees and the few groups of wasps to which bees are closely related. The family Ampulicidae contains around 170 living species, which are classified in two subfamilies and six genera. The genus Ampulex is the most speciose genus of the family, and is found worldwide.

Identification: The family Ampulicidae can be distinguished from the other families of apoid wasps by the combination of several key features:

1. Tarsal claws always toothed along the inner margin (In other groups, they are sometimes toothed but are often entirely simple and untoothed)
2. Two spurs at the apex of the tibia of the middle leg (Other apoid wasps may have one, two, or even none)
3. Jugal lobe of the hind wing small or entirely absent (Present or absent in other apoid wasps, but usually quite large when it is present)
4. Petiolate segment of the metasoma is composed of both a tergum and a sternum (separates Ampulicidae from the similar-looking family Sphecidae)

This species in particular is recognized amongst ampulicid wasps by the metallic turquoise body and the red femora of the second and third pairs of legs. The combination of these features separate this species from those that are closely related.

Natural History: Ampulicid wasps are hunters of cockroaches, and provision their nests with live roaches for their larvae to feed on. This species is known to attack roaches of the genus Periplaneta among other groups. These wasps are particularly notable for their exceptional behaviors within hunting their prey. The wasp is often much smaller than the roaches it hunts, meaning they have to get creative within how they capture a roach host. An ampulicid wasp usually disables the escape reflexes of its prey before dragging it back to its nest, typically by injecting the nervous system with venom and then severing the antennae of the roach. After disabling and incapacitating the roach, the ampulicid “leads” it back to its burrow by dragging it by the head. Once in the nest with wasp’s eggs, the roach waits, paralyzed and unable to move, until the eggs hatch and the new ampulicid wasp larvae eat it from the inside out.

View This Species On:
iNaturalist: https://www.inaturalist.org/taxa/348362-Ampulex-compressa/

References:

• Aguiar, A. P., Deans, A. R., Engel, M. S., Forshage, M., Huber, J. T., Jennings, J. T., … & Miko, I. (2013). Order Hymenoptera. In: Zhang, Z.-Q.(Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013). Zootaxa, 3703(1), 51-62.
• Goulet, H., Huber, J. T. (1993). Hymenoptera of the world: An identification guide to families. Ottawa: Research Branch Agriculture Canada.
• Kim, K. C. (1969) The Frost Entomological Museum, Bulletin of the Entomological Society of America, 15(2): 82.
• Williams, F. X. (1942). Ampulex compressa (Fabr.), a cockroach-hunting wasp introduced from New Caledonia into Hawaii. Proclamations of the Hawaiian Entomological Society. 11: 221–233.

This week’s wasp is the ibaliid wasp species Ibalia anceps! This species was first described by the American entomologist Thomas Say in the year 1824.

Figure 1: Ibalia anceps female, lateral habitus

Figure 2: Ibalia anceps female, dorsal habitus

Figure 3: Ibalia anceps female, anterior view

Figure 4: Ibalia anceps female, face

Taxonomy: This species is a member of the superfamily Cynipoidea and the family Ibaliidae. The superfamily Cynipoidea also includes the families Cynipidae (gall wasps), Figitidae, Liopteridae, and Austrocynipidae. The family Ibaliidae contains 20 living species, which are classified in three genera. There are two species of the family, both in the genus Ibalia, in the eastern United States: Ibalia anceps Say, 1824 and Ibalia leucospoides (Hochenwarth, 1785).

Identification: This species is recognized as a member of the superfamily Cynipoidea primarily by the wing venation, as cynipoids have a distinct large, somewhat-triangluar radial cell on the leading edge of the forewing, and generally complex venation on the rest of the forewing. Many cynipoids also have a laterally flattened metasoma. Ibaliids are also the largest members of Cynipoidea – most cynipoids are tiny and only a few millimeters long! This species is recognized as a member of the family Ibaliidae by the long, thin radial cell of the forewing (see Figure 5 below), which is many times longer than it is wide, and by the shape of the metasoma, which is very long, very flat, and distinctly blade-like. Ibalia is the only genus of the family in North America. The two eastern United States species of Ibalia are very easy to tell apart, as Ibalia leucospoides has a black head and mesosoma with a deep red metasoma, and Ibalia anceps is entirely yellow and brown.

Figure 5: Ibalia anceps forewing, indicating the radial cell (in red)

Natural History: Ibaliid wasps are rarely encountered. They are all parasitoids of horntail sawflies of the family Siricidae. Ibalia anceps is a parasitoid of the siricid genus Tremex, which is fairly common throughout North America. Not much else is currently known.

View This Species On:

BugGuide: https://bugguide.net/node/view/63912

iNaturalist: https://www.inaturalist.org/taxa/470470-Ibalia-anceps

References:

• Aguiar, A. P., Deans, A. R., Engel, M. S., Forshage, M., Huber, J. T., Jennings, J. T., … & Miko, I. (2013). Order Hymenoptera. In: Zhang, Z.-Q.(Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013). Zootaxa, 3703(1), 51-62.
• Goulet, H., Huber, J. T. (1993). Hymenoptera of the world: An identification guide to families. Ottawa: Research Branch Agriculture Canada.