Monday, 2 September 2013

September already

September is good time to look for leaf mines: most of them are now fully-developed, and the larvae have mostly pupated.

The mine of the micromoth Heliozela resplendella is one of the most interesting examples:
Mine of Heliozela resplendella on Alder

The miner starts around point C, on the central vein. It then proceeds via a side vein to point B, where it leaves the vein and mines the soft tissue to point A, where it enters another side vein which it mines back towards the central vein at point E. Having reached the central vein, the miner continues to mine it until it reaches point D, at the petiole. It then reverses direction and mines the central vein back to point E, where it enters a side vein. It then makes a very short blotch along that vein before cutting an oval piece of leaf at F. It then descends to the ground, and uses the oval piece of leaf as a pupation wrapper.

This preference for the woody vein material over the soft leaf tissue is a reversal of the usual mining preferences, where soft tissue is eaten, but veins are used for navigation, rather than food.

It should be noted that in some instances of this miner the journey via the soft tissue is omitted: the only externally-visible sign of the mine in those instances is the oval cutout in the leaf.

A single specimen of the July High-flyer came to light:

July High-flyer
These can be separated from the Autumn Green Carpet by the round shoulders and the black diagonal slashes at the rear corner of the wings. Can you see the black slashes? Nope, neither can I: they're worn off.


The Weaver of Grass said...

I never for one moment imagined Stuart that a moth's wings wore off.

stuart dunlop said...

Weaver, it's not so much a matter of the wings wearing off (although they do slightly), but it's the fact that the wings are covered with coloured scales. When these scales wear off, the pattern disappears, or becomes 'vague'. Unfortunately for those of us who try to identify them, the wear is quite often in the places - like wingtips - that carry distinguishing features. Moths that have battered off window panes can sometimes have very few scales left.

The Weaver of Grass said...

Thanks for the answer to the moth problem Stuart - could you provide the answer to another problem? If you have time could you please pop over to my blog and see if you can identify the picture - sure you can. I have great faith in your ability.

stuart dunlop said...

Weaver: done!