Fired up by brimstones and buckthorn

CATERPILLARS of the brimstone butterfly have only one source of food – the leaves of the buckthorn bush – and females of the species will fly miles to lay eggs on its leaves.

For this reason males of the species also tend to hang around the same species of bush, waiting for a chance to mate.

Lack of buckthorn bushes and trees is thought to be the main reason for east Suffolk being sparsely populated by the brimstone.

Now, in a project involving the county branch of Butterfly Conservation, the Suffolk Naturalists’ Society and Ipswich Borough Council, enthusiasts are preparing to hand out free trees in a further attempt to boost populations of what is one of Britain’s most beautiful butterflies.

Matt Berry, project spokesman, said: “The aim is to encourage people to plant the brimstone’s caterpillar food plant in their own gardens, allotments etc, in order to help the butterfly spread further across the county - especially east Suffolk where it is very infrequent.”

The group is offering people free trees - in the form of small whips donated by Crown Nursery at Woodbridge - and the information needed to plant and care for them.

“In return we ask for planting locations and any future sightings of butterflies, eggs or caterpillars. This will help us plot where the butterfly is being seen and thus measure the success of the project,” said Matt, a wildlife ranger with Ipswich Borough Council whose interest in wildlife was sparked as a child always playing out of doors.

This is the second project within 13 years aimed at trying to boost brimstone populations in east Suffolk.

It was in 1998 that the Suffolk branch of Butterfly Conservation, along with Ipswich Organic Gardeners Group, Ipswich Wildlife Group and the wildlife rangers of Ipswich Borough Council, launched the original Brimstones and Buckthorn initiative.

It proved a success. In just two years more than 2,000 bushes of both common, purging buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus) were planted in the target area of Suffolk and the results were particularly spectacular in Ipswich’s parks and gardens.

Female brimstones soon homed in with the first one turning up during fine sunny weather in a garden at Bildeston on May Day, 1999.

Bushes were planted until 2003 with the result that the butterflies were seen in increasing numbers in the area. Between the year 2000 and 2004 there were 242 records of brimstones in east Suffolk. Between 2005 and 2009 there were 644 recorded sightings.

However, brimstone numbers are still not thought to be at a sustainable level in the east of the county and, with several “black hole” areas where the species is unrecorded, a new initiative has been launched which aims to encourage people to get involved in some wildlife gardening and wildlife conservation.

“This time around, we’ll be using the internet to collate data and plot the location of any brimstones using bushes planted during the initiative.

“People will be able to view their records of plantings and sightings online with a map containing details of all the other records from the scheme. It also has the potential to provide far more up-to-date feedback and to find out what other insects are associated with buckthorn.

“To start off, we’ll be sending out bare-rooted whips to the public along with planting details this winter. Bushes will be free although any donations will be gratefully received.

“Participants will be asked to monitor growth and to look out for brimstones and egg-laying activity over the following two years,” said Matt, 38, who has always lived in Ipswich and who completed a conservation management course at Otley College before obtaining his ranger job with the borough council.

Another aim of the project is to raise awareness of the merits of the buckthorn bush for other species.

Buckthorn flowers provide nectar which seems particularly attractive to bees and hoverflies.

Later in the year, shiny black berries provide a valuable source of food for birds.

Along with other species the green hairstreak occasionally deposits eggs on common buckthorn and the holly blue uses alder buckthorn as well as its more normal larval food plants.

A number of moth larvae are also occasionally found on the bushes.

“It’s great news that these days buckthorn is often found in hedgerow mixtures sold in garden centres, but there is still room for improvement.

“And we mustn’t forget that buckthorn is not the only butterfly friendly-plant. From buddleia to lavender there’s plenty you can plant in your garden to attract and help butterflies and moths,” Matt added.

The “black hole” areas of east Suffolk with little or no brimstone activity include Felixstowe and district, Ramsholt, Orford, Bawdsey, Sudbourne, Wrentham and Covehithe.

The value of wildlife gardening and in particular the fascination for insects, was emphasised by TV presenters Jimmy Doherty and Steve Backshall, at “Jimmy’s Farm”, near Ipswich, earlier this year.

At the opening of Mr Doherty’s tropical butterfly house at Wherstead, three buckthorns were ceremonially planted in the adjacent wildlife garden to increase the availability of habitat for native butterflies.

Rob Parker, Suffolk’s county butterfly recorder, said the absence of buckthorn bushes in east Suffolk was likely to be as much the result of soil conditions as the removal of hedgerows in previous decades.

“The common purging buckthorn does well on chalky soil while the alder buckthorn likes damp conditions. In the sandlings area of east Suffolk soil conditions tend to be neither damp-rooted nor chalky,” he said.

In his talks to wildlife and gardening groups as well as WIs and other organisation, Mr Parker has given details of the brimstone project and a significant number of people have signed up to the scheme.

The new brimstones ands buckthorn initiative, being part-financed by private donors, is open to anyone in East Anglia. If you’re interested please email brimstones@suffolkbutterflies.org.uk or telephone 01473 436096