Buckfast. Report from the Entomology Section

Being situated on the sheltered southern flank of Dartmoor and with its mix of geology the Buckfastleigh area is rich in wildlife and is particularly well-known for its invertebrates. The limestone hill and its associated caves are home to the bristletail Trigoniophthalmus alternatus, a rare species of the twilight zone of cave entrances. In Britain it is rarely found outside of its stronghold in the limestone caves of south Devon. The roadside verges around the hill and other flower-rich meadows such as those along ‘The Queen of the Dart’ above Buckfast are home to a large population of marbled white butterflies Melanargia galathea and the rarely seen six-belted clearwing moth Bembecia ichneumoniformis. On warm summer evenings an impressive chorus of great green bush-crickets Tettigonia viridissima males can be heard calling around the town. The call of this, our largest member of the grasshopper family, is so loud it can be heard from up to 100 metres away!

Close to the town are some ancient woodlands. The best known of these is Hembury Woods which are situated above the River Dart as it descends towards Buckfast Abbey. The rich oak woodlands abound with insect life, the most obvious of which are the red wood ants Formica rufa. On quiet days in spring and summer it is possible to hear a quiet rustling sound as thousands of them go about their business amongst the leaf litter. Look closer at their nests and you may be lucky to find a scarce seven-spot ladybird Coccinella magnifica. Closely related to its familiar cousin this species has a special association with wood ants and seems to be immune to their attacks. It feeds on the aphids which the ants farm on small birch trees near their nests.

Birch is the food plant of the impressive sawfly Cimbex femoratus which is occasionally seen along woodland rides in May. The adjoining grasslands were home to the last British population of the large blue butterfly Maculinea arion which sadly became extinct in the 1970s. Efforts to re-establish a population here using Swedish stock have unfortunately failed. The area is still rich in butterflies and has nationally important colonies of pearl-bordered fritillary Boloria euphrosyne and high brown fritillary Argynnis adippe both of which have larvae which feed on violets. It is also home to one of our largest true flies, the hornet robber fly Asilus crabroniformis. This 2.5 centimetre long fly is an ambush predator. In late summer it waits on dung piles or ant hills and intercepts flying insects such as dung beetles and grasshoppers.

At night large dung beetles of the genus Geotrupes and Anoplotrupes abound in the woods and surrounding meadows, and along with the cockchafer Melolontha melolontha provide food for the famous colony of greater horseshoe bats Rhinolophus ferrumequinum which inhabit the area. Moths are also an important part of the bats’ diet and many species abound here, the most special of which are also some of the smallest. The tiny leaf-mining micro moth Ectoedemia heckfordi was recently discovered here as a species new to science by DA member and micro lepidoptera recorder Bob Heckford. Two other small and very beautiful micro moths are also of special note, Oecophora bractella and Schiffermuelleria grandis. Both have larvae which feed on dead wood. A special search has to be made to find the adult moths which fly very early in the morning, in the first rays of sunshine through the oaks on warm days in June.

John Walters

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