Spilomena exspectata VALKEILA 1957
The small (2.5–3.5mm) species within the genus Spilomena probably suffer, more than any other crabronids, from under-recording. This is on account of their diminutive size, making initial discovery and capture less likely and then observation of difficult microscopic features more challenging. Rearing specimens from samples of nesting material is a useful way of searching for these wasps.
This species is not directly included within Lomholdt (1984) other than as a note to separate it from the Fennoscandian speciality Spilomena exspectata Valkeila, although Bitsch et al. (2001) treat exspectata as being synonymous with beata. This view is also held by Vikberg (2000). There is much taxonomic uncertainty throughout this genus.
In Britain, it is only known from England, with the majority of records from Surrey and Kent. Elsewhere, very thinly scattered records stretch west to Devon and north to Durham. Richards (1980) describes the species as being “moderately common”, although current data suggest this may be a generous summary.
It is seemingly restricted to central and northern Europe, including Germany, Switzerland, Austria, the former Czechoslovakia and Yugoslavia, Scandinavia and parts of Russia (Bitsch et al., 2001). From this it can be inferred that it is on the western edge of its range in England.