Thursday, 13 May 2010

Drumboe plethora

Drumboe is an ancient woodland on the west bank of the river Finn, a very short distance away from the town centre. Despite its proximity to shops, schools, church and football ground, it is home to many scarce species: perhaps five or six of the species that I have discovered to exist in Ireland come from this site.

As I mentioned earlier, no time is wasted when new leaves emerge. Today's pictures are all leaf-based and tomorrow I'll show the flowers and insects I found on my visit.

Leaf-miners come from 4 families: beetles, flies, micromoths and wasps. The instant the new Beech leaves appear, the mines of the beetle Orchestes fagi can be found. The mines are very distinctive, initially mining a gallery from the leaf centre to the edge where a blotch is formed.

The above image shows two mines ready for pupation to take place only a few days after the leaves have unfurled. There are a few reasons for mines to be so quick:
  • Multiple generations - speed is important if other generations are to follow before the leaves fall
  • Soft leaves - fresh, young leaves will be easier to mine and digest than old, hard ones
  • Parasite avoidance - the less time in the mine, the less time to be found
In the early stages, the Orchestes mine can easily be confused with Stigmella sp. micromoths, due to the single line of frass that runs down the centre of the mine, but the terminal blotch is distinctive:

Staying with Beech, this is an atypical specimen of the mine of the micromoth Stigmella tityrella. Haphazard or oddly-shaped mines are often a sign of parasitization - this mine is usually confined to run between two of the main leaf veins.

Honeysuckle leaves are host to a large number of flies and wasps. This appears to be a mine of the fly Aulagromyza hendeliana, based on the widely-dispersed frass drops:

Holly would seem to be an ideal leaf to build a home, but only one of our species mines it. Phytomyza ilicis:

Birch leaves are even more recent than Beech leaves, and yet this Incurvarea pectinea micromoth is already about to leave the leaf to pupate:

As I was examining other Birches for mines, I noticed these yellow/orange bumps on a few leaves of one specimen. They reminded me very much of the lumps made by Taphrina torquinetii on Alder, so I checked the reference and found Taphrina betulae, which is a very rarely-recorded fungus.

This should not be confused with the much more common Taphrina betulina which makes the very recognisable 'Witches broom'.

First Irish Record (told you Drumboe was good).

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