Pseudomalus auratus (Linnaeus, 1758)

Paukkunen, Juho, Berg, Alexander, Soon, Villu, Odegaard, Frode & Rosa, Paolo, 2015, An illustrated key to the cuckoo wasps (Hymenoptera, Chrysididae) of the Nordic and Baltic countries, with description of a new species, ZooKeys 548, pp. 1-116 : 15-16

Taxon classification Animalia Hymenoptera Chrysididae

Pseudomalus auratus (Linnaeus, 1758) Figs 26, 27, 28, 32, 33

Sphex aurata Linnaeus, 1758: 572.

Pseudomalus auratus : Kimsey and Bohart 1991: 265.

Diagnosis.

Length 3-6 mm. Both sexes have a bicoloured body with a blue-green or violet head and mesosoma, and a red (or rarely entirely greenish) metasoma with green reflections (Fig. 26). The species is very similar to Pseudomalus triangulifer , but the antennal segments are shorter (Fig. 33) and the body is usually smaller. The apical notch of T3 is also deeper and more rounded dorsally (Fig. 32).

Distribution.

Denmark, Estonia, Finland, Latvia, Lithuania, Norway, Sweden. Common. - Trans-Palearctic/Holarctic: from western Europe and northern Africa to China, Korea and Japan. Introduced accidentally to North America ( Kimsey and Bohart 1991).

Biology.

Habitat: forest margins and clearings, gardens and parks. Often found on sun-exposed leaves of deciduous trees and bushes. Adults are attracted to honeydew of aphids and occasionally visit flowers of Apiaceae and Euphorbiaceae ( Rosa 2004, our own obs.). Flight period: May to August. Host: cavity-nesting crabronid wasps that prey on aphids, e.g. Passaloecus corniger Shuckard, Passaloecus eremita Kohl, Passaloecus insignis (Vander Linden), Passaloecus gracilis (Curtis), Passaloecus monilicornis Dahlbom, Passaloecus singularis Dahlbom, Passaloecus turionum Dahlbom, Pemphredon inornata Say, Pemphredon lethifer (Shuckard), Passaloecus lugens Dahlbom, Pemphredon lugubris (Fabricius) and Passaloecus rugifer (Dahlbom) ( Schenck 1856, Benno 1957, van Lith 1958, Brechtel 1986, Blösch 2002, our own obs.), but also Diodontus tristis (Vander Linden), which is a soil-nesting species ( Blösch 2002). Host records mentioning other crabronids, such as species of Rhopalum Stephens, Trypoxylon Latreille and Crabro Fabricius, are questionable, because the prey does not consist of aphids in these taxa. Females oviposit in aphids before they have been captured and brought to the nest by the host (our own obs.). A similar behaviour has been observed also in Omalus biaccinctus ( Winterhagen 2015) and postulated for Pseudomalus triangulifer ( Veenendaal 2011).