At a time when so much news on insects is poor, we have more good news; another couple of ‘fantastic firsts’ for the village.
The first ‘first’ is a nationally scarce hoverfly – Parasyrphus nigritarsis (Zetterstedt, 1843) – a beneficial stripy yellow and black pollinator that has had its first record noted for the whole of the vice-county of Oxfordshire, much to the delight of the experts running the UK’s Hoverfly Recording Scheme. Unlike most of its relatives which have aphid-eating larvae, the larvae of this one prefer the taste of beetle eggs and larvae – in this case those of the metallic Green Dock Beetle, Gastrophysa viridula (De Geer, 1775), as well as a couple of other leaf beetle species, which are consumed with great gusto. A few of its eggs were found nestled amid the bright yellow egg batches of the beetle on the profusion of dock plants down by the river last month and were retained for rearing; a lone adult female was also seen. A return trip revealed more eggs so we hope this species will prove to be established here.
The other ‘first’ is another fly, a delightful tachinid (a ‘parasitic fly’) that goes by the wonderful name Gymnosoma rotundatum (Linnaeus, 1758), a fitting name for it with its balloon-like abdomen, that was found in a lay-by nectaring on hogweed, a veritable ‘pollinator magnet’ of a plant. This lovely fly has been spreading slowly north and west from its original range in the far southern counties. This is its first record for West Oxfordshire; the few previous Oxfordshire entries being south of Abingdon.