It only seems like yesterday that I was talking about how behind the blossoming of the Horse Chestnut trees were this Spring when compared to last year (see blog https://www.natureguy.blog/post/step-back-in-time). Now, the trees are bearing their prickly fruits, albeit small at the moment but a sign that Autumn is not far around the corner.
What did baffle me when I was inspecting the young fruit was the number of markings which appeared to be damaging the leaves of all the trees I came across. At first, I assumed it was a disease but after checking online I discovered that these unusual but in my opinion strangely pretty markings were made by the larvae of the moth Cameraria ohridella. The female moth can lay up to 180 eggs on new leaves and when hatched the larvae feed on the leaves, once the larvae pupate and become a moth in the Spring, the whole cycle starts again. After a sustained period of infestation, the tree can become weakened and although not harmed it can become susceptible to other diseases.
It is not surprising that I had not really noticed this leaf damage before as the first recorded moth in this country was only in 2002, its origins possibly from its native southern Europe where it was first recorded in the 1970’s.
Next time you come across a Horse Chestnut tree, stop to inspect the leaves for markings, if you look carefully you may even see the larvae feasting on the lush leaves.
Another interesting sighting this week was on a young Oak tree in Trench Meadow and this was the clusters of Oak Apple Galls produced by the action of the Oak Apple Gall Wasp. The wasp is very small and the female wasp will lay an egg on the branch or twig and the gall is created by the tree itself in response to the action of the wasp laying the egg. Inside the gall, there are a number of chambers, each housing a larva which eats its way out. The gall produces nutrients for the developing larvae inside which is also protected by the gall.
This is a fine example of parasitisation in action where one species uses the other to aid and promote its growth and development.
Make sure to study an oak tree more closely next time and study these remarkable structures.
Very interesting r kid