In these tough times it's great to be able to share some positive news for one of our target species. The Marsh Fritillary is one of our rarest butterflies and for many years has been known to breed at just one site in Gloucestershire. This precarious outlook however has recently been given a boost thanks to some encouraging survey results.
Although not on the wing until May, one of the best ways to survey for the Marsh Fritillary is to look for its larvae. Although tricky to find, the larvae (caterpillars) that hatch out in late summer helpfully spin conspicuous webs within the vegetation which make them easier to spot. These webs can contain many larvae as they group together to feed in relative safety on the leaves of Devil’s-bit Scabious, their larval food-plant.
After overwintering tucked down in the vegetation, the larvae then emerge again in their webs the following February as temperatures begin to warm up. By carrying out surveys for the webs at this time of year we can see how many survived the winter and by estimating the number of larvae within each web, we can get an idea of how our Marsh Fritillary populations are faring.
Our surveys in Gloucestershire this February took place at both the known breeding site and another site nearby where breeding hasn't been recorded for several years, even though adults are occasionally seen.
At the original site a total of 14 webs were counted this year, a marked improvement on 8 in 2019, while at the second site (and after a painstaking search) our Conservation Officer Julian managed to find a single web containing approximately 50 larvae!
This is a hugely exciting result and is a great reward for the landowners and all the volunteers who have worked incredibly hard alongside Julian, clearing scrub and reinstating grazing to help improve the habitat for this rare butterfly.
It is great to be able to say that we now have two breeding sites in Gloucestershire for the Marsh Fritillary so let’s hope this success continues!
Limestone's Living Legacies Outreach Officer.
Would you like to help these incredible species? There are numerous ways in which you can:
- Why not volunteer for Back from the Brink? Check out our events page for opportunities near you.
- Help us to spread the word of this species, and the others we will be helping over the next 3 years, by sharing our message across our Twitter, Facebook, Instagram and YouTube pages. Follow us: @naturebftb.
- Finally - help support the work we do across England by donating. Our impact will be greater with your help.