The cow wheat shieldbug was recently found in a woodland by Genevieve Tompkins who works at the Rare Invertebrates in the Cairngorms partnership project.
This is only the eighth record for the bug in Scotland, with previous sighting being recorded between 1866 and 1989.
The rare insect is considered to be “nationally scarce” across the UK, with worrying declines in the south-east of England over recent years.
Ms Tompkins said: “One of the great things about this project is that, while looking for the focus species, our volunteers come across other rare insects too.
“Insects are hugely under-recorded, but give us vital clues as to the health of our habitats.
“It is sad that this bug has suffered from a decline in traditional woodland management.
“However, there is hope, with diverse woodlands once more becoming a key feature of the Cairngorms National Park.
“It would be brilliant if more people could look out for the bug, submitting their records through the iRecord website.”
The cow wheat shieldbug has a black body featuring two distinctive white spots.
The bug relies on cow wheat as a food plant and, although this plant is common in Scotland, the insect needs it to grow in a sheltered, warm micro-climate, usually on sunny rides and glades in woodlands.
These habitats rely on traditionally managed woodlands with diverse structures, creating sheltered open areas.
It is believed that a decline in such places is one of the reasons why the bug has fared badly over past decades.