Where the butterfly flutters
01 August, 2013
Last week took me to Aberdeenshire to carry out surveys of some of our sites there. Passing through Perthshire on the way back, I stopped off at Balvaird Castle, on the road between Auchtermuchty and Bridge of Earn.
Balvaird is unusual among Scottish tower houses in that it retains all the elements that comprised a residence of the landed gentry in the late Middle Ages. You can see it in its full context – surrounded by outer and inner courtyards and associated outhouses (or at least their foundations), a formal walled garden (today without its planting), and a large walled ‘pleasance’, or park, where the family could indulge in leisure pursuits such as archery and hawking.
What makes Balvaird interesting in terms of its wildlife is the abundance of flowering plants and the invertebrates they support. The really special part is a small patch of unimproved grassland around the car park, which supports a colony of increasingly rare northern brown Argus butterflies. Flowers include rock rose, spignel, devil’s-bit scabious, bird’s-foot trefoil and bitter vetch.
Bird’s foot trefoil is an important source of nectar for the northern brown Argus, but rock rose is the main food plant for its larvae. Colonies of the northern brown Argus are always associated with this plant.
The butterfly species was first noted in 1793 a collector called Jones took several specimens from Arthur’s Seat in Edinburgh. It figured two years later in William Lewin’s The Papilios of Great Britain, under the name “Brown White Spot”.
The colony at Arthur’s Seat was decimated by Victorian collectors, who were said to send wee boys out to collect specimens for their collections. Mysteriously, however, they have reappeared, probably introduced by a butterfly enthusiast as eggs or larvae.
Another butterfly commonly found here is the ringlet. In addition there are usually many small black-winged moths, called chimney sweep moths for obvious reasons.
Spignel is another rare plant found here. Spignel produces large, grooved fruits which taste strongly of curry. It was an unpopular plant with dairy farmers as it flavoured the milk! Like other umbellifers, it is an important food plant for insects.
Bitter vetch is a member of the pea familly, also called heath pea. In medieval Scotland, it was used as an appetite suppressant at times of food shortage. It was commonly used up until the 18th century, when potatoes became a substancial part of the diet.