CTA update - Hymenoptera in Oxfordshire, 2024

May 2024

Ivan Wright

As with other insects that fly well, most Hymenoptera – especially the wild bees and wasps – are nosey and adventurous! Like Bark Beetles and Flesh Flies they are quick to ‘sniff out’ a new opportunity. In springtime, most Hymenoptera are hunting for flowers, prey and nesting sites, and so are excellent indicators of change, both in climate and habitat. For climate change, records of Hymenoptera from Oxfordshire are particularly important because the county sits on the north-western limit of the British and European ranges of many species, including most of the bees and wasps mentioned here.

Recently, there have been various notable bee and wasp records from Hymenoptera surveys in Oxfordshire, and the results from three Conservation Target Areas (CTAs) are highlighted here: Blenheim and Ditchley Parks CTA, Shotover CTA and a meadow near Cuxham, just outside of the Chiltern Escarpment North CTA.

Blenheim and Ditchley Parks CTA

High Park, the private area of ancient oaks on the Blenheim Estate, has recently undergone a 5-year biological survey encompassing a wide range of taxa. Although not expected to be particularly rich in Hymenoptera, the survey did reveal notable host and ’cuckoo’ bee pairs. Several Big-headed Mining Bees Andrena bucephala were recorded togetherwith their specific cuckoo, Long-horned Nomad Bee Nomada hirtipes, showing that these scarce bees are well established at High Park. The Hawk’s-beard Nomad Bee Nomada facilis was only added to the British fauna in 2017, having been ‘split’ from a long-established species. The host bee in Britain for this cuckoo is only tentatively suggested to be the Hawk’s-beard Mining Bee Andrena fulvago, yet at High Park both were recorded at the same time and place.

For solitary wasps, Chrysisterminata was confirmed at High Park, a Ruby-tail Wasp recently split from Chrysis ignita, and so far, has only a few UK records. The very rare (and long - 4cm with ovipositor!) parasitic Ichneumon wasp Pseudorhyssa alpestri was also recorded.

Lookout for The Natural History of Blenheim’s High Park due for publication later this year.

Ruby-tailed Wasp (Chrysis ignita agg)

Cuxham Meadow

A small south-facing meadow at Cuxham, now recovering from an assortment of uses, was surveyed during 2022 and surprisingly returned excellent results. Four specimens of The Ridge-saddled Carpenter Bee Heriades truncorum were recorded (also found at High Park). Until a few years ago this bee was restricted to south-eastern counties of England, and was very rare in Oxfordshire. Now it seems to be expanding its range westward quite rapidly; the Oxfordshire records are currently some of the most westerly sightings in Britain.

Four species of Ruby-tail Wasp were recorded in the meadow, three of which are very close to their north-western limit in Britain, including Hedychridium roseum and Hedychrum niemelai, which both occur at Shotover. The third species, Chrysis gracillima, is rare and listed as ‘RDB2- Vulnerable’, and may be the first record of this species in the county.

Heriades truncorum

Shotover CTA

Records of Hymenoptera from Shotover began in the 1890s, but since then the southern slopes have succeeded from pasture to woodland and have become degraded for the regionally-important species of short acidic grass. However, ongoing conservation work is resetting this succession and Hymenoptera are a key (and rapid) indicator of improving habitat richness.

For example, before 2023 the Large Gorse Mining Bee Andrena bimaculata had not been recorded on Shotover for about 100 years; it has now reappeared, especially where bracken has been removed recently to expose the sandy soil. The abundance of Short-fringed Mining Bee Andrena dorsata together with habitat restoration at Shotover has been attracting the Variable Nomad Bee Nomada zonata. Having arrived from the continent only 8 years ago (2016), this cuckoo bee is rapidly spreading westward. Also, the Bee Wolf wasp Philanthus triangulum has reappeared on Shotover after an apparent absence of 20 years.

Shotover’s new celebrity species has been the Yellow-shouldered Nomad Bee Nomada ferruginata which arrived this year and proved that, sometimes, public recreation can be compatible with wildlife conservation. In this particular case, where an area of bare soil used by mountain bikes was ‘sculpted’ by Shotover Wildlife for soil-nesting invertebrates, and was soon adopted by the rare bee. An article about this appeared in British Wildlife magazine in 2023, and can be viewed here.

UK Pollinator Monitoring Scheme

For anyone interested in contributing to an important national pollinator study and occasionally spending ten minutes watching flowers and insects in good weather – go to https://ukpoms.org.uk/fit-counts

Bee ID and Meadow Survey May 2019

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