Trichrysis cyanea (Linnaeus,1758)
Description and notes
Identification key and general biology are given in Morgan (1984). The only entirely metallic blue wasp in Britain.
This species shows a widespread distribution from Cornwall to Kent and north to North Yorkshire with isolated records from Cumbria (Skirwith) and Scotland (Perth and Kinross).
Overseas, the wasp occurs throughout Europe (including Norway, Sweden, Finland, Denmark, The Netherlands, Belgium, Luxembourg, France, Spain, Germany, Austria (to 960m), Italy, Poland and Hungary) and the rest of the Palaearctic, but not Japan.
Status (in Britain only)
This species is not regarded as scarce or threatened.
Associated with open habitats with aerial nesting sites of its hosts such as wooden fence and gate posts, dead trees, logs and tree stumps, and holes in mud and cob walls.
Recorded from May until September but mainly during June and July. There are a very few records from April and October. The males and females have the same flight period.
Wild carrot and wild parsnip. It has also been recorded on laurel leaves.
It has been reared from its hosts Trypoxylon figulus and T. attenuatum. Other hosts seem to be Pemphredon lethifera, Stigmus pendulus, Hylaeus pectoralis, Heriades truncorum, and Chelostoma florisomne.