Chrysis equestris Dahlbom, 1854

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 : 80-81

Taxon classification Animalia Hymenoptera Chrysididae

Chrysis equestris Dahlbom, 1854 Figs 80, 89, 112, 134, 151

Chrysis sexdentata ? Dahlbom, 1831: 30, not Christ, 1791.

Chrysis zetterstedti of authors, not Dahlbom, 1845.

Chrysis equestris Dahlbom, 1854: 307.

Chrysis fasciata of authors, not Olivier, 1790.

Diagnosis.

Length 7-10 mm. Both sexes have a mostly dark blue or black, partially violet, body with green reflections on the frons, margins of the pronotum, mesoscutum, mesoscutellum and mesopleuron. The tergites have contrasting golden red or golden green bands posteriorly (except on the apical rim), which are especially wide laterally on T1 and T2. The colour and form of the bands is quite variable, usually they are wider and more reddish in the female than in the male. The species closely resembles Chrysis zetterstedti , but is characterised by the following differences: the black spots of S2 are narrower, usually not extending to the lateral margins of the sternite (Fig. 112), T5 of the female (on ovipositor) is broader and has a longitudinal medial groove (Fig. 89), the head is broader, especially in female (shortest distance between the compound eyes is slightly longer than the diameter of an eye) (Fig. 151), the gonostyle is shorter, the cuspis is apically curved (not straight) (Fig. 134), and the propodeal tooth is slightly convex or straight ventrally (not lobate).

Distribution.

Estonia, Finland, Lithuania, Norway, Sweden. Rare. - Trans-Palearctic: from western Europe to Russian Far East (Sakhalin).

Biology.

Habitat: forest margins, clearings and gardens with sun-exposed dead wood. Adults are usually found on sun-exposed dead tree trunks and stumps, most often of Populus , but also of Salix , Betula and Alnus , rarely Picea and Pinus . They also fly near log piles, telephone poles and walls of old wooden buildings ( Frey 1915, Linsenmaier 1997). Flight period: mid-May to early August. Host: Discoelius dufourii Lepeletier and Discoelius zonalis (Panzer) ( Vespidae ) ( Pärn et al. 2014, our own obs.).