18
Suffolk Natural History, Vol. 31
CONSERVING THE BARBERRY CARPET MOTH IN SUFFOLK N. E. SIBBETT The barberry carpet, Pareulype berberata Schiff, is one of Britain's rarest animals, found breeding at just three sites in the country. The most well known site is in Suffolk, near Bury St Edmunds, many miles from the recent discoveries in Hampshire and Gloucestershire. Eggs are laid on leaves on the wild barberry plant, Berberis vulgaris, on which the caterpillars feed exclusively. In captivity the caterpillars will eat cultivated varieties of Berberis although there is a high rate of mortality, perhaps because the cultivated varieties have thicker cuticles and tougher leaves. This may explain why this rare moth has not become widespread even though cultivated varieties of Berberis are common in gardens.
Historical background The Suffolk population of the barberry carpet moth was first discovered in the 1860s (Morley, 1937). A threat to the site in the early 1970s stimulated C. W. Pierce (1971, 1972, 1974, 1975) to take caterpillars and rear them in captivity for eventual relocation elsewhere. However, the new populations did not survive. Further details of the history of the moth up to 1989 can be found in Waring (1989). In August 1991 a stubble fire in the adjacent fieid severely scorched threequarters of the barberry plants (Waring, 1991). This was at a time of year when the caterpillars would have been freely feeding and vulnerable to the effects of the fire. If the fire had been a few weeks later the pupae would have been much safer in the leaf litter under the barberry. The survivors (if any) were left undisturbed in the hope that the population would recover. Over the next few years, as the barberry grew again, the number of barberry carpet moths could have increased.
The 1994 Survey In 1994, English Nature decided to survey the Suffolk site, assess the population of the moth and take active measures to help it survive. The site was surveyed by Dr Paul Waring (1994), on contract to English Nature, on June 28th, 1994. He held a Standard Bigneil beating tray of 1.02m2 (33"x43") under the barberry foliage, and knocked the foliage five times with a heavy stick. This common technique is used to dislodge caterpillars from the leaves and catch them in the tray. No barberry carpet caterpillars were found, suggesting that it could be extinct at this site. About half of the total volume of the barberry was not surveyed because it was out of reach, so some caterpillars may have been present but not found. It is unlikely that pupation would have occurred by the survey date as captive populations had not pupated then. However, the caterpillars are notoriously hard to find and a negative result does not mean that it is absent. In 1987 a similar survey found no caterpillars but they were readily found in 1988.
Trans. Suffolk Nat. Soc. 31 (1995)
CONSERVING THE BARBERRY CARPET MOTH
19
Present conservation work English Nature has adopted four priorities for conservation of the barberry carpet moth:(i) A repeat survey is needed to help confirm the continued existence of the moth in Suffolk. (ii) Competition from adjacent shrubs and climbers such as blackthorn, Prunus spinosa, and old man's beard, Clematis vitalba, is being reduced by clearance work. This is being carried out voluntarily by Mr Chris Scott. (iii) Forest Enterprise's Westonbirt Arboretum in Gloucestershire are propagating barberry from cuttings taken from Suffolk in order to replace those plants lost in the fire of August 1991. Wild barberry is very difficult to grow from cuttings. In one or two years there should be a good number of barberry plants to plant out at the Suffolk site, and possibly nearby. The more barberry there is, the greater chance of survival the moth has. (iv) A captive stock of barberry carpet moths is being held by four zoos, including London Zoo, to ensure its survival in Britain and to provide individuals for releasing into the wild when appropriate. New release sites for the moth could be elsewhere in Suffolk, or replacements could be released at the original site if repeated surveys indicate that the longknown population has finally become extinct. Thanks to the help and support of the owners of the barberry carpet moth site, the moth's future now looks much more hopeful.
References Morley, C. (1937). Final Catalogue for the Lepidoptera of Suffolk. Memoirs of the Suffolk Naturalists' Society, Ipswich. Pierce, C. W. (1971). Barberry Carpet Moth. Trans. Suffolk Nat. Soc. 15, 273. Pierce, C. W. (1972). Barberry Carpet Moth Second Report. Trans. Suffolk Nat. Soc. 15, 511. Pierce, C. W. (1974). Barberry Carpet Moth Third Report. Trans. Suffolk Nat. Soc. 16, 316. Pierce, C. W. (1975). Barberry Carpet Moth Fourth Report. Trans. Suffolk Nat. Soc. 16, 394. Waring, P. (1989). Conserving the Barberry Carpet Moth in Suffolk. Trans. Suffolk Nat. Soc. 25, 37. Waring, P. (1991). Moth Report. British Wildlife. 3(1), 49. Nicholas Sibbett, English Nature, Norman Tower House, 1-2 Crown Street, Bury St. Edmunds, Suffolk IP33 1QX
Trans. Suffolk Nat. Soc. 31 (1995)