Stilbops ruficornis (Gravenhorst, 1829)

Verheyde, Fons, Hoekstra, Paul, Libert, Pierre-Nicolas, Meijer, Hilco, Ketelaere, Augustijn De, Vandaudenard, Thibaud, Belgers, Dick & Brosens, Edwin, 1880, Two hundred and five ichneumonid wasps reported for the first time in Belgium and the Netherlands (Hymenoptera: Ichneumonidae), Belgian Journal of Entomology 122, pp. 1-142 : 115-116

Stilbops ruficornis (Gravenhorst, 1829) (Fig. 62 A–B)

Stilbopinae and Stilbops spp. are not easily characterised as a subfamily or genus, but most species can – with some experience – be recognised by habitus. Stilbops spp. have their apical flagellar segment usually longer than the preceding one and their areolet is obliquely quadrate or narrowly pentagonal (BROAD et al., 2018).

Stilbops ruficornis has a black mesosoma and a predominantly red metasoma, with the exception of the first tergite which is partly blackish and the apical tergites which have yellowish white bands. Its ovipositor is black and somewhat upcurved apically (Fig. 62A). This species is often easy to recognise in the field because of it specific ecology. It swarms in groups in the vicinity of Knautia arvensis , where it searches for eggs of its lepidopteran host Nemophora metallica (Poda, 1761) ( Lepidoptera : Adelidae ) in the flower heads (BROAD et al., 2018; Fig. 62B). There is no doubt the parasitoid wasp is rarer than its host, but even then it is also clear there are important gaps in our current knowledge on the distribution of the species. Although we have to admit the specific habitat is scarcer in Flanders, still a bit striking is the absence of data near the Dutch border, while all observations from the Netherlands stem from the same (bordering) southern part of the country (Nederlands Limburg).

First report for the Netherlands; confirmed in Belgium.

MATERIAL EXAMINED:

BELGIUM: • 1 ♀; Viroinval, Le Franc Bois (NA); 50°05’24”N 4°33’58”E; 12/viii/2010; H. Wallays leg.; field observation; F. Verheyde det. (ObsID: 49485409). • 1 ♂; Rochefort, Le Gros Tienne (NA); 50°06’18”N 5°05’54”E; 2/vii/2017; J. Preud’homme leg.; field observation, oviposition on Knautia arvensis next to living specimens of Nemophora metallica (Poda, 1761) ; F. Verheyde det. (ObsID: 141663329). • 1 ♀; Bailièvre (HA); 50°04’13”N 4°14’57”E; 16/vii/2017; S. Claerebout leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 141689470). • 3 ♀♀; Fauvillers (LX); 49°53’28”N 5°45’06”E; 21/vi/2020; W. Declercq leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 194783213). • 1 ♀; Torgny (LX); 49°30’35”N 5°28’53”E; 25/vi/2020; F. Verheyde leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 195171863) […].

THE NETHERLANDS: • 1 ♀; Simpelveld (LIN); 50°50’14”N 5°58’12”E; 8/vii/2010; T. Bakker leg.; field observation, flying next to living specimens of Nemophora metallica ; F. Verheyde det. (ObsID: 165700135) . • 5 ♀♀; Eys , Piepert (LIN); 50°49’39”N 5°55’16”E; 24/vi/2014; A. Wijker leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 86162753) . • 2 ♀♀; Wahlwiller / Nijswiller, Kruisberg (LIN); 50°48’48”N 5°56’37”E; 13/vii/2019; S. Lamberts & A. Wijker leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 176567411) . • 1 ♀; Voerendaal , Kunderberg (LIN); 50°51’48”N 5°57’00”E; 14/vii/2019; S. Lamberts & A. Wijker leg.; field observation, oviposition on Knautia arvensis sp.; F. Verheyde det. (ObsID: 176351473); Fig. 62 A–B .