Coll and Tiree provided a ‘hive’ of activity, with experts converging on the islands during National Insect Week.
Visitors included Bob Dawson representing the Bumblebee Conservation Trust and a group of four entomologists; including Darren Mann (Oxford University Museum of Natural History), Geoff Hancock (Hunterian Museum, Glasgow), Garth Foster (Aquatic Coleoptera Conservation Trust) and Jeanne Robinson (Glasgow Museums), sponsored by Scottish Natural Heritage (SNH) and the Glasgow Natural History Society (GNHS) to survey the island’s insects and to investigate sightings of a very rare and special beetle.
Walks and talks were organised on both islands and lots of people came along to find out more about the rare and interesting insects they share their islands with. There was even interest from the national media; a film crew came out to Tiree for a day to film for the National Lottery Awards, who have supported the Bumblebee Conservation Trust’s work on the islands. The visiting group were particularly interested in the short-necked oil beetle, Meloe brevicollis, thought to be extinct in the UK since the 1940s, before making a surprise re-appearance in Devon in 2007. No one expected that the next sightings would come last year from Coll, but a digital photograph sent to the beetle expert Darren Mann indicated that this was the case. These unusual looking beetles are dependent on solitary bees for survival. After hatching out of the soil, the beetle larvae sit around on flowers waiting for visiting bees to grasp onto. They must get to a bee’s nest, where they kill their young and feast on their pollen stores. Their host bee in the Inner Hebrides is the Northern Colletes bee (Colletes floralis) – also a rare species!
Whilst the bees are doing very well on both islands, no oil beetles were found on Tiree. Coll however was found to be extremely active this year, with about 40 beetles being recorded from 4 different coastal sites over 2 and a half days. A local high school teacher from Tiree came along to the beetle talks and was keen to teach his students about the beetles and enlist their assistance in surveying for them. These beetles can be relatively easily spotted along coastal paths and often identified from good photographs. Photographs can be submitted to the experts directly or via the RSPB wardens. The public can play an invaluable role in monitoring the status of these insect treasures in the islands. The general insect survey has also been revealing, resulting in many new insect records including at least a dozen species that have not been recorded from Coll and Tiree, including the diving beetles Ilybius guttiger and Hygrotus novemlineatus and the cranefly Erioptera nielseni. You can find out more about the insect survey on the National Insect Week blogs: http://blogs.nationalinsectweek.co.uk/jeannerobinson/
Hot on the heels of this peculiar beetle was Britain’s rarest bumblebee, the great yellow bumblebee Bombus distinguendus. Rather more mobile than the oil beetle, the queens emerge from hibernation mainly in June, and during the week were busy collecting pollen and searching for nests. Tiree and Coll are important areas for this species in the UK, largely because of the machair and its management.
After spotting a couple of queens on Coll, including one sheltering behind an Escallonia hedge in a strong wind, Bob Dawson of the Bumblebee Conservation Trust arrived at Ceabhar, Sandaig, to be shown a photo of a great yellow bumblebee by Duncan and Polly. Remarkably, it had flown into the restaurant! This was a good omen, with one or two more sightings, including one in John Fletcher’s garden, before a Bumblebee Safari at Balephetrish saw beautiful weather and a good turnout by people and bees alike. There were perhaps as many as 8 queen great yellow bumblebees among the dunes, mainly feeding on kidney vetch. An earlier Bumblebee Safari at Totronald on Coll had missed out on the great yellow bumblebee this time around, but the two other rare bumblebee species were present: moss carder bee Bombus muscorum and red-shanked carder bee Bombus ruderarius.
Coll and Tiree are the only places in the UK where these three rare bumblebees can be seen together, and if anyone would like more information on how to identify and record bumblebees please get in touch at the address below. We really need to know how the numbers are doing on the islands from year to year. Keep up to date with what’s happening with the great yellow bumblebee on ‘Bob’s blog’ http://gybb.bumblebeeconservation.org/
All of Coll and Tiree’s bumblebee species were out and about, including the unusual Barbut’s cukoo bumblebee Bombus barbutellus, which takes over the nests of other bumblebees. It was mainly the large, queen bumblebees that we were seeing, of the eight different species on the islands, but there were a few of the (smaller) workers out and about, which would be from nests started by queens back in May. These would have emerged from hibernation before the great yellow bumblebee, back in April and May.
There was also a bumblebee on Coll (at Cornaigmore) that ought not to be on the islands – a buff-tailed bumblebee Bombus terrestris. This is still a common species on the mainland, but it seems the sea crossing is not too serious a barrier for this large, mobile species. There are regular reports of bumblebees visiting boast a few miles from shore, which are usually the commoner species. Who knows, perhaps some of Coll and Tiree’s speciality bumblebees can make it to the mainland and establish nests there? Almost as quickly as they arrived, the experts reluctantly departed, convening on the M.V. Hebridean Isles for a quick debriefing over lunch. We were all agreed that these are very special islands indeed, and with a lot of analysis to do back at our respective bases.