The search for Bombus distinguendus, rare bee of the Scottish isles
The once-common great yellow bumblebee is now found only in parts of north and west Scotland.
People in the Western Isles and northern Scotland are being urged to look out for one of the UK's rarest bumblebees to help save the species from extinction.
The Bumblebee Conservation Trust is asking people to hunt for the great yellow bumblebee to create a picture of where it can still be found.
The great yellow bumblebee (Bombus distinguendus) was found across the UK until the 1960s, but after suffering a massive decline is now only found in a few places in Scotland's northwest, in machair grasslands and other flower-rich areas on the north coast and some of the islands.
The Trust is now asking people to look in 28 specific grid references - each measuring 10x10km - at sites ranging from Tiree, the Uists, Harris and Lewis, across Sutherland and Caithness on the mainland, to Orkney and Shetland between June and September.
Katy Malone, Bumblebee Conservation Trust's Scotland Conservation Officer, said: "We need to know more about where the great yellow bumblebee is holding on, so we can take action to protect it before it's too late. Anyone can get involved with this citizen science initiative to save a species.
"Because this iconic insect's last havens are in some of the country's most far-flung corners, we don't have enough volunteers to find and record its whereabouts.
"So we're asking people holidaying in the northwest Highlands and Islands this year - as well as those living in these beautiful places - to help."
The Trust's Great Big Great Yellow Bumblebee Hunt, which begins on Saturday June 8, features 28 grid squares where the great yellow used to live, but which have not been checked in recent years.
Anyone able to visit these sites is asked to record all the bumblebees they find, whether Great Yellows or not.
If they think they have found a great yellow bumblebee, they are asked to take photographs to help experts confirm identification.
The great yellow is a large bumblebee entirely covered with golden-yellow hairs - apart from a black band across the thorax between the wing bases.
Good places to look are areas of flower-rich grassland, particularly those with clover, thistles, vetches and knapweed, which the great yellow loves - ideally when it is sunny and warm, and not too windy.
A map with a full list of the grid squares is available on the Trust's website, with details of how to record sightings, tips to identify bumblebee species, and advice on visiting remote locations.
The Trust said that the UK's bumblebee populations have "crashed" over the past century, with two species becoming extinct and only 24 remaining.
Populations are threatened from the loss of flower-rich habitats as well as from pesticides containing neonicotinoids, which are used by the forestry industry to kill pine weevils.