Insect Portraits – Hawthorn Shieldbug
These splendid examples of the Hawthorn Shieldbug Acanthosoma haemorrhoidale were photographed in Assynt this autumn. Gwen Richards found one on locally-collected rowan berries at Torbreck (NC0824) on 6th September 2019, and David Haines spotted the others on walls at Culkein Drumbeg (NC1133) on 17th and 24th October. Shieldbugs are amongst the most showy of the ‘true bugs’ (Hemiptera-Heteroptera), and this is one of the largest, at 12-16mm.
Hawthorn Shieldbug is something of a misnomer up here, where hawthorn is scarce. It shows a distinct preference for rowan in the north, but is also found on holly, cotoneaster and other berry-bearing shrubs. The over-wintering adults emerge from April and lay their eggs through to July; the generation of the year is adult from August onwards.
The earliest local record I know of was made by Les Pearce at Badnaban (NC0720) on 30th April 2010 and I had one in my Stevenson screen at Nedd (NC1331) on 29th May 2015. The species has been moving north since the 1950s and, according to Stephen Moran, who has a particular interest in bugs, has now reached Berriedale Braes on the east coast (ND12), a whisker south of Nedd.
At least 640 species of ‘true bugs’ occur in the British Isles. They include 43 species of shieldbugs, some 10 of which have been noted in the Highland area. The only others recorded from Assynt are the slightly smaller birch shieldbug Elasmostethus interstinctus and the equally large, but brown, red-legged shieldbug Pentatoma rufipes, but the parent shieldbug Elasmucha grisea may also occur.
For further information, consult the British Bugs web-site (www.britishbugs.org.uk), which has an on-line identification guide and a huge gallery of illustrations. Please photograph and report any that you come across, since we appear to be on the northern frontier for the group.