Description and notes
First found in Britain in 1978 by M. Edwards. An important paper on this species is that by Else (1997). See also Dicker (1982). A key to European species groups of the genus Passaloecus is given by Merisuo (1974).
Southern England; from Dorset to Kent and, more locally, northwards to the east Midlands and Norfolk.
Widely distributed in Europe, but rare (Lomholdt 1975-76).
Status (in Britain only)
Listed by Shirt (1987) as Rare (RDB3), but revised by Falk (1991) to "not thought to be native".
This species is found in various habitats but needs the presence of pine trees as a source of resin and aphid prey.
Late May to late September, but particularly June to July.
The prey is Homoptera of the family Lachnidae, including Cinara pinea, a species living on pine (Lomholdt 1975-76).
In Britain, P. eremita nests in pine bark, in burrows in the bark and dead sapwood of pine and deciduous trees, and in abandoned beetle borings in posts, the nest entrances frequently being surrounded by a ring of small drops of resin (a feature which is possibly unique to this species (G.R. Else, pers. comm.)). The nests are also sealed with resin, which hardens to a characteristic white or off-white plug (Else 1997). In Denmark, the species has been found nesting in the hollow stems of common reed used in thatching roofs, sometimes in very large numbers. There are usually 4 or 5 cells per reed stem, terminating in a vestibular cell. The last constructed cells usually contain males, which are the first to emerge. Burrows in bark or old timbers frequently have one or two cells only (M. Edwards, pers. comm.). A previously occupied stem or beetle boring may be re-used (Lomholdt 1975-76).
Flower visits are not known for this species.
Else (1997) reported the ichneumonid Poemenia notata as a parasitoid, reared from a nest of Passaloecus eremita. Abroad, the chrysidid wasps Omalus aeneus and Trichrysis cyanea are recorded as cleptoparasites or parasitoids, as are the ichneumonid Perithous scurra (= mediator) and the dermestid beetle Megatoma undata (Lomholdt 1975-76).
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