Thursday, 30 May 2019


We are more or less at the end of May. Insects have now been galling plants and creating leaf mines to the point where they are more obvious and the creatures responsible can be identified with some degree of confidence.

I went for a constitutional around Stefen Hill Pocket Park earlier today and the first thing to catch my eye was indeed a mine.
The larvae of Aulagromyza hendeliana mine honeysuckle leaves
and are very common. Stefen Hill Pocket Park, 30 May, 2019

It was on honeysuckle and the insect responsible was a fly, Aulagromyza hendeliana. Its mine, which generally hugs the leaf margin, is distinctive with grains of frass (poo) in the form of evenly distributed grains. Not a lot of people know that - nor, I am sure, do they particularly want to.

In fact, despite the title of today's blog, I failed to find many mines, but plant galls were more evident. Cecidology, the study of plant galls, takes in many disciplines. Some botanical knowledge is essential and the galls themselves can involve many groups of creatures: wasps and flies (entomology) and mites (acarology) are often responsible. Then there are fungi, particularly rusts, so theoretically mycology is involved too, although I admit that at the level at which I record galls it is not really necessary.

Oaks are galled by a particularly large number of creatures and the picture shows the work of a gall (Cynipid) wasp, Andricus curvator. Its galls can confusingly take several forms depending upon which part of the plant has been selected.

The cynipid wasp, Andricus curvator, is a common creator of galls
on oaks. Stefen Hill Pocket Park, 30 May, 2019
There was also the tatty but unmistakeable remains of a gall from last year. It was a Ramshorn gall, Andricus aries, caused by another cynipid wasp. I had to stand on tiptoe to photograph it, so apologies for the quality.

Andricus aries forms the distinctive Ramshorn Gall. This is a specimen
lingering on from last year. Stefen Hill Pocket Park, 30 May, 2019
Speaking of oaks, I had hitherto only found one specimen but today a spotted a second. It was not at all typical and I hesitate to put a name to it. It is rather like a White Oak, Quercus alba, a North American species sometimes planted for ornament, with leaves turning red in the autumn. And yet...

Quercus alba? I'm not convinced but if acorns form they may provide an
answer. Stefen Hill Pocket Park, 30 may, 2019
Anyway, I'll keep an eye on it for acorns.

Ash trees are galled, but the example I photographed is the work of a psyllid bug, Psyllopsis fraxini. It causes the leaflet edge to develop a reddish coloured roll.

Few ash trees escape the bug, Psyllopsis fraxini. Stefen Hill
Pocket park, 30 May, 2019.
And that was about it. There were smallish galls on Field Maple which I won't bother the reader with, and the only other thing to trouble my camera was a tight ball of spiderlings.

A feast for birds! Spiderlings on a goosegrass stem.
Stefen Hill Pocket Park, 30 May, 2019
They were on the tip of a goosegrass stem and almost certainly were Araneus diadematus offspring. They will soon start to disperse and statistically only a couple should survive to replace their parents. This profligacy troubled Alfred, Lord Tennyson:

                             Are God and Nature then at strife,
                             That Nature lends such evil dreams?
                             So careful of the type she seems,
                             So careless of the single life.

Who would be a spider?


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