Isle of Wight last stronghold for rare rediscovered moth

Conservationists from the Hampshire and Isle of Wight Wildlife Trust (HIWWT) say the Reddish Buff Moth (its Latin name, Acosmetia caliginosa) — a rare moth species found only on one site in the UK, has been recorded for the first time in four years.  

Two of the moths were found during the HIWWT’s annual moth survey programme, held at a sanctuary site on the Isle of Wight.

The rare Reddish Buff Moth, rediscovered on the Isle of Wight. (Image: Iain Outlaw)

And thanks to the work of the HIWWT, in partnership with the Isle of Wight AONB, Butterfly Conservation, Amazon World and the Wildheart Animal Sanctuary, the Reddish Buff Moth has a chance to increase its numbers.

The last adult moth was found in 2019, raising hopes the new finds will provide a future for the endangered moth.  

Jamie Marsh, Director of Nature Recovery, Wilder Wight and Wilder Seas, for the HIWWT, said: “This is a significant and reassuring find, as we were concerned about the status of this endangered species. 

"Covid massively impacted our survey efforts in 2020 and 2021, when only one single larvae was found, so to discover that the Reddish buff moth is still persisting is very exciting. 

“It is a difficult moth to survey for and requires a lot of time and effort.

"It doesn’t readily come to light traps and can easily hide away, so it is very fulfilling to discover two individuals.

"We were getting nervous the species had been lost, so to find it this year, and have it verified by the UK’s leading expert, is a big relief.” 

The moth's last remaining stronghold, within a closed sanctuary site for wildlife, contains an ideal mix of its most favoured habitat, along with saw-wort, the sole larval food plant.  

The Reddish Buff Moth's flight period is from April through to July. Its copper-coloured forewings and pale red hindwings helps it to blend in with its surroundings and attract potential mates.

The species is medium sized, with a typical wingspan of up to 15mm and weighs just 23mg. 

“The Reddish Buff Moth epitomises the challenges many of our rare species face," Jamie adds.

"Restricted to a single site with specific habitat requirements and a single food plant, it seems to have everything against it, yet it is still persevering, thanks to the hard work of the team, a dedicated group of volunteers and site partners Isle of Wight AONB, Butterfly Conservation, Amazon World and the Wildheart Animal Sanctuary."

"The HIWWT’s remaining focus for the site is to continue to restore and improve the habitat for the moth and other species."

The discovery comes as the UK is about to celebrate National Moth Week, between August 22-30.