The tree bumblebee originates from continental Europe
Bumblebee conservationists are urging gardeners to check whether a bee, indigenous to continental Europe, has made its way to Scotland.
Bombus hypnorum, or tree bumblebee, has already been spotted in England.
However, scientists have yet to receive a confirmed sighting of the species north of the border.
The tree bee was first spotted in the UK by the Stirling-based directors of the Bumblebee Conservation Trust (BBCT) in 2001.
Its arrival, thought to be the first new species of bumblebee for more than 150 years in the UK, comes despite a dramatic decline in the numbers of others.
Unlike many of the more common domestic bumblebees, tree bumblebees have a distinctive light brown thorax (the middle segment of their body) while their abdomens are black with a white tip.
They nest in tree holes and bird boxes.
In the last 70 years, two of the UK's 24 species of bumblebee have become extinct while six are currently on the endangered list.
The decline has been put down to a lack of habitat after changes to farming and landscaping saw 98% of the UK's flower-rich habitats wiped out, leaving the insects with very little food in the wider countryside.
Dr Ben Darvill, who was one of the first to see the tree bee during a Wiltshire field trip, said there had been an unconfirmed sighting of the tree bumblebee in Fife.
He added: "Against a backdrop of bee decline and habitat loss, it's nice to have something positive to talk about.
"We are very interested to see how quickly the tree bee spreads and surely it is only a matter of time before the first sighting is confirmed in Scotland."
Conservation charity A Rocha is set to embark upon a national survey to see how far the insects have spread across the British Isles.
Dr Darvill urged anyone who caught sight of the insect to take a digital photograph of it and submit a record of it via the A Rocha website.