Having once been widespread across the south and east of England, the known range of the scarce vapourer is now restricted to just a few locations in South Yorkshire and Norfolk. The species decline and current rarity means it is a nationally rare and endangered species. Yorkshire Wildlife Trust has investigated the lifecycle of the scarce vapourer and its current range for the last two years and have applied for funding to allow us to continue this research for a further two and a half years (as of March 2026).
The scarce vapourer moth
The Scarce Vapourer (Orgyia recens) is a punk rock caterpillar covered in colourful plumes, with a wonderfully unusual lifecycle. Sadly, this is an increasingly rare and threatened species.
Scarce Vapourer Larva on Bramble leaf showing distinctive orange plumes, black ‘antennae’ and ‘tail’ plumes and orange side stripe. Credit: Martin Warne.
So what do we know?
As with all moths, scarce vapourer begin life as a tiny egg, developing into a larva (that’s the scientific name for a caterpillar!). At first the larvae are tiny and look completely black, they have long hairs which they can use to be blown by the wind, allowing them to disperse among vegetation. The larvae eat the leaves of many types of deciduous trees and shrubs, such as willows and brambles, and grow in size, developing their characteristic plumes of bright orange hairs on their back along with black ‘antennae and tail hairs. Once they are of adequate size, the larvae create a cocoon of silk with their hairs mixed in and begin to pupate (the process of metamorphosis in an adult).
Scarce Vapourer larvae nearing the stage of preparing a cocoon to pupate in. Credit Andrey Ponomarev
When males emerge from their cocoon the begin searching for a mate, flying on warm sunny days. They are largely brown and very similar to their close relative the common vapourer/the vapourer (Orgyia recens). Unlike common vapourers, their wings have brilliant flashes of orange and delicate white patterns.
Adult females are unlike anything you might expect, practically wingless and resembling a round, grey ball off fluff - certainly not what you might imagine a moth to look like. Rather than flying around and looking for a mate, the adult female sits on top of her cocoon and secretes a pheromone to attract males. The energy she saves from not developing flight muscles and wings, along with her sedentary lifestyle, she puts into growing hundreds of eggs (up to 800!).
The cycle starts once again when the female lays her eggs, caterpillars hatch around the start of august and spend the rest of summer feeding. In autumn they attach themselves to a leaf and enter a deep sleep (diapause), waking again the next spring to continue their lifecycle.
Adult Scarce Vapourer moths, the male is mostly brown with orange patches at the forewing edges while the female has no functional wings and is grey and downy and significantly larger than males. Credit Andrey Ponomarev
Scarce vapourer appear to prefer wet areas such as fens and bogs, areas typically with peaty soils and areas of scrubby tree growth. Thorne Moors in the Humberhead Levels currently appears to provide just what these invertebrates require and is a strong hold. Older records suggest they used to be found in hedgerows but lots of these sites have been developed, however, they may still be holding out in places we have not yet surveyed.
Why are they declining?
Honestly, we don't know! Common vapourer are still widespread and have a very similar lifecycle, though are perhaps less reliant on areas of wetland. It is possible that there is a subtle difference between the species around the time of entering a winter sleep which means scarcevapourer are more vulnerable to seasonal vegetation management (such as hedgerow cutting). Common vapourer seem to favour pupating and overwintering away from the leaves which may take them out of harm’s way. Scarce vapourer remain on the leaves, and so if management takes place prior to leaf fall, they are likely to fall victim.
Wetlands have been lost across England through draining and those remaining are often fragmented and small. Small wetlands may not provide enough of the scrubby habitat they seem to enjoy best and fragmentation creates isolated populations. Small populations, particularly those isolated from others, are particularly at risk of dying out. A single season with adverse conditions or clearance of scrub in the exact location of a population can result in extinction from that site. For example, Thorne Moors covers a large area with many areas of scrub and multiple scarce vapourer populations. If a population in one area of the Moor dies out due to habitat management, there remains populations elsewhere, which can repopulate the area of the extinct population should it become suitable in the future.
Another issue with isolated populations is that they have no choice but to breed with their close relatives, in many species this can reduce their ‘fitness’, breeding out traits which would help them survive. We are currently undertaking genetic tests on specimens found in museums and comparing them to the population of today to understand whether this is occurring in scarce vapourer populations.
How can you help?
We are continuing our surveying efforts, however, there is a large area to cover requiring a big effort to locate populations of such a rare species. We are particularly interested in finding populations outside of the places we know them to be. South Yorkshire (particularly outside of Thorne Moors), Norfolk, Lincolnshire and Nottinghamshire are particular areas of interest.
Keep a look out and if you see caterpillars which resemble those of scarce vapourer, please get in touch with some pictures (ideally one from above and one from the side) and information about the location so we can verify your record. You are most likely to see these in May through to June.
If you would like to get involved in our surveying efforts please also get in touch with us. Below there is link to a document which details the methodology you should follow and information which is helpful to record so we can better understand this charismatic species. This all helps in our effort to conserve scarce vapourer and protect it from extinction.
If you think you’ve found scarce vapourer caterpillars or would like to get involved in surveying, send an email to jim.horsfall@ywt.org.uk.