Friday, 2 August 2019

Mines and galls

There were insects a-plenty in Stefen Hill Pocket Park earlier today. I'll be looking at the specimens taken when time allows but for now I am going to examine the galls and leaf mines noted on my walk.

First up was a clump of Red Valerian with the distinctive mine of Liriomyza strigata. Although it is polyphagous, attacking a range of plants, the mine caused by the larva always tends to follow the midrib of a leaf.

Leaves of Red Valerian had been mined by Liriomyza strigata.
Stefen Hill Pocket Park, 2 August, 2019
The insect in question is a member of the Agromyzidae, a family of insects responsible for many a mine throughout the civilised world (plus the states of Georgia and Mississippi).

This long, sinuous gallery mine was on oak and is the work of a moth, Stigmella basiguttella. Common on oaks everywhere it has been called the Base-spotted Pigmy but of course no one uses the name.

Looking like a meandering river, this mine is the work of  a moth,
Stigmella basiguttella. Stefen Hill Pocket Park, 2 August, 2019

Mines are now to be seen on leaves everywhere but galls are appearing too. A distinctive one is Alder Tongue, Taphrina alni. I have mentioned this species before but I couldn't resist photographing a nice specimen today.

Protruding from an alder catkin is the visible part of the fungus,
Taphrina alni. Stefen Hill Pocket Park, 2 August, 2019

Unusually it is a fungus and causes a distortion of the female catkins. Currently it is quite brightly coloured but withered brown-black specimens often remain on the catkins for months.

I examined the some oaks in the expectation that I would find knopper galls, Andricus quercuscalicis, present. Instead some of the acorn cups had been galled by Andricus grossulariae, a new wasp for the pocket park.

A shaft of sunlight through the trees highlights the gall on an acorn cup.
Andricus grossulariae is the culprit. Stefen Hill Pocket Park,
August, 2019

Interesting (well, interesting to me) mines were found on Coltsfoot and Cinquefoil but I will not try the patience of my readers (over 70 logged on yesterday to peruse my ramblings). Instead I'll put the kettle on - far more important than blogging!

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