One day after observing a female Passaloecus corniger closing her nest in a dead branch of Butterfly bush (Buddleja davidii) I revisited the nest location. This time a different wasp grabbed my attention; a female ichneumon wasp Poemenia collaris ^[1,4] showed a clear interest for the branch. It is a known parasite of Passaloecus corniger ^[2,3].

Every nest location was inspected and she halted at a few. There she would position herself above the nest and parasitize it. Among the nests also the one from the previous day (Fig 1).

To locate a nest the wasp walks around feeling the area with her antennae spread an moving independently. When she finds a potential nest the antenna are held in a parallel curve as she sniffs out the nest (Fig 2). After parasitizing the nest she will sniff it out ones more with het antennae in this position.

The days after the wasp has not been seen at the branch but turned up at other locations like the bee hotel.

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Literature

¹ Nederlands Soortenregister

² Peeters, T.M.J., C. van Achterberg, W.R.B. Heitmans, W.F. Klein, V. Lefeber, A.J. van Loon, A.A. Mabelis, H. Nieuwen-huijsen, M. Reemer, J. de Rond, J. Smit, H.H.W. Velthuis, 2004. De wespen en mieren van Nederland (Hymenoptera: Aculeata). – Nederlandse Fauna 6. Nationaal Natuurhistorisch Museum Naturalis, Leiden, knnv Uitgeverij, Utrecht & European Invertebrate Survey – Nederland, Leiden.

³ Blösch, M. (2000). Die Grabwespen Deutschlands – Lebens‐weise, Verhalten, Verbreitung. 71. Teil. In Dahl, F.: Die Tierwelt Deutschlands. Begr.: 1925. – Keltern (Goecke & Evers). – 480 S. 341 Farbfotos. ISBN 3‐931374‐26‐2 (hardcover). DM 98,–. Zool. Reihe, 78: 353-353. https://doi.org/10.1002/mmnz.20020780208

⁴ KANDERS, Jon. Swedish species of the Poemeniinae (Hymenoptera: Ichneumonidae). Degree project in Biology, Master of science, Biology Education Centre, Uppsala University, and Swedish Museum of Natural History, Stockholm, 2009.