It was a beautiful day in early October (see my post A summer day in October – 7 October 2012), it seemed as if nature was trying to hold onto summer but the signs of impending autumn were all around. I saw the beautiful autumn colours of this vine and I took a quick picture before I was distracted by a passing butterfly, a beautiful yellow one that enjoyed seeing me chase it from perch to perch without every letting me get close enough for a shot. I forgot about my lovely vine in the heat of the chase.
It was not until later that I made my connection between the beauty of the vine leaves and a beastie I had managed to photograph earlier. I was rather contented that I had at last got a photograph. It is very tiny, just less than one centimetre long, and extremely nimble. I had caught glimpses of it in the undergrowth during the summer but it had hopped out of sight before I had got a good view of it, much less a photograph!
The Latin name reflects the strange bison-like shape of this creature and it was not until I found out its life cycle that I made a connection with my red vine leaves.
The larvae of Stictocephala bisonia hatch out mid-May to mid-June and feed on herbaceous plants such as dandelions, clover and plantain without causing too much harm to the plants and after five moults become adults. By mid-July to mid-August the adults are ready to breed and can be found in the vineyards (also in orchards as they are partial to apple trees too) and the females lay their eggs on the young vines on wood between 1-3 years old usually. The females make a longitudinal slit in the bark and deposit about six eggs each side of the incision. The eggs are incubated in the safety of the plant until the developed larvae drop to the earth the following year to restart the cycle.
Unlike the herbaceous plants that the adults and larvae feed on, the vines can suffer from their role as nursemaid to the insects’ eggs. The incisions of the egg laying female and the larvae cause a disruption of the vascular sap bearing system of the vine and result in the spectacular reddening of the leaves. Heavy and repeated infestation can result in weakening of the vine. The best treatment is to cut and burn all infected parts.
If I had thought a little more about why a single vine plant should be turning such and unusual colour I would have realised at the time that something was amiss – it was all the fault of that yellow butterfly.
(Many thanks to the l’Institut Français de la Vigne et du Vin (IFV)for the above information)