Heather Beetles on the Chayne

Heather beetle larvae on the Chayne - plants turning red in the background.
Heather beetle larvae on the Chayne – leaves turning red in the background.

After a maddening collision between lightning and the horribly fragile infrastructure that BT maintains in Dumfries and Galloway, I have only recently come back into the world of the internet after an absence of almost ten days – (ten days without that wobbly stop/start rural internet that inexplicably costs exactly the same as lazer-fast urban internet while being prone to staggered and often extended absences).

During my absence, work has continued on the Chayne, with the latest and most interesting discovery being the realisation that heather beetles are in the process of annihilating the new heather growth in my enclosure. Well documented on this blog as the “heather laboratory“, the little enclosure was put up in the winter of 2010 to demonstrate the level of grazing pressure on the hill, and also to let me play around with a small area of plants. During the past few years, the heather laboratory has taught me a great deal about my own heather, as well as the plant species which respond to controlled grazing – it even put on quite a healthy show of pink flowers in August last year on a hill that is otherwise green and bobbing with grass heads at that time of year.

Visiting the enclosure last night with Simon Thorp of the Heather Trust, I was quite surprised when he bent down and gathered up a handful of heather beetle larvae from an area of heather that was just starting to look a little redder than it usually does. On a very close inspection (hands and knees), I managed to catch several dozen grubs when I returned this morning, and noticed that the heather is looking very shabby in some places. As soon as I got my eye in, I was able to spot grubs in a range of different sizes, giving themselves away only by the movement of their absurdly shiny black heads. Watching the larvae themselves, it seems that the action of their eating is less a caterpillar-like chomp but more a rhythmical fraying, scraping the leaves up and down and leaving them looking rather rough and tatty. It is this damage that causes heather plants to become dehydrated, leading in severe cases to the death and extensive disappearance of otherwise healthy plants.

These pests have obviously been in this area for a few days. Many heather shoots are looking very weary, and some plants already seem to have given up the ghost altogether. Even the plants which have been only slightly nibbled are showing signs of great unhappiness, and rather than focus their attention on producing buds and flowers, those promising little white cones have withered away as the plant martials its resources, abandoning reproduction in an attempt to stay alive.

Over the next few weeks, I can expect the beetle damage to become more conspicuous. Beetle damaged plants turn a foxy red colour in late summer and early autumn, which will give me the opportunity to assess the extent of the problem. I can rest more easily because if the worst comes to the worst, I will have lost half an acre of heather. Given that some estates can lose thousands of hectares in a single year, it becomes clear what a problem beetle damage can be.

I’ve been working with the Heather Trust on their heather beetle research over the past two years, and just as a side note, it is crucial that anyone with beetle damage on their own land helps to record the incident using the Heather Beetle Survey, which is available on the Trust’s website – there are so many black holes in our understanding of heather beetle, and the more information the Heather Trust can gather about outbreaks across the British Isles, the more likely it is that we can devise ways of managing the problem.

Lots more information on the Heather Trust website.

 

Early signs of damage - will these plants survive?
Early signs of damage – will these plants survive?
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