Oak Mildew, 22-Spot Ladybird and Burnet Moth Caterpillar

Tuesday, August 09, 2011 Adam Tilt 2 Comments


I've just got back from a walk around my local patch which would have delivered a nice sunset if it wasn't for a large bank of cloud that rolled in at the most inopportune moment. There was still plenty to look at though including the largest gathering of Swallows that I have yet seen there. At least thirty individuals were hunting over the freshly mown fields which may not sound that many to some, but for here it represents a significant increase over the norm. Up on Bryn-bach-Common things were very quiet with just a few Meadow Pipits and a large flock of Carrion Crows on their way to the evening roost.

On the road from the common down towards Pontlliw we noticed that certain areas of the hedgerows were covered in a white substance. At first glance I assumed that a passing vehicle has perhaps splashed mud up from the road which had since dried, but closer inspection revealed that we were in fact looking at some sort of fungal growth.

Oak Mildew and Burnet Moth Caterpillar

As can be seen in the photo above the main species to be infected were the young Oak trees, which has led me to the diagnosis of a significant infestation of Oak Mildew. This is a white powdery fungus that usually appears in late summer and can retard the growth of young plants or even kill tree seedlings. Up until 1907 much of Europe was free from Oak Mildew epidemics but it became much more widespread after introduction from North America. An interesting article regarding this pathogen and its life cycle can be found here. Those with eagle eyes will have noticed a Burnet Moth caterpillar hanging on to the bottom edge of the leaf, one of many in this area.

Literally on the next leaf across from the one shown above there was sat a bright yellow Ladybird, something I have never seen before.

22-Spot Ladybird

It is called the 22-Spot Ladybird and usually has, as you can probably guess, about 22 black spots. Interestingly this species is particularly fond of feeding on mildew which I imagine explains its proximity to the Oak Mildew infestation.

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