Martin Harvey's picture

Phytomyza ilicis - Brandon Hill

Observed: 24th January 2011 By: Martin Harvey
Berkshire Moth GroupFSC - Field Studies CouncilSoldierflies and Allies Recording SchemeBuckinghamshire Invertebrate Group
Invertebrates expert
Phytomyza ilicis - Brandon Hill
Description:

For once there weren't many leaf-mines on this particular holly, but it wasn't quite devoid of them.

Identifications
Species interactions

No interactions present.

Species with which Holly Leaf Gall Fly (Phytomyza ilicis) interacts

Comments

RHoman's picture

ilicis?

This is certainly not a typical mine. The rounded shape suggests something has spread from a central point and the amount of dead tissue suggests something like an infection (fungal?) in the leaf rather than ilicis. Most of the other iSpot observations of this species are from later in the year when the mines are more deveoped, but in late January, even with the cold weather, a bit more corridor development could be expected.

Robert Homan

RHoman's picture

Further thought

Could this be an old mine in which the larva has died at an early stage. This would mean that the leaf has been on the tree since early last spring - I'm not sure about the timing of holly leaf drop.

Robert Homan

Martin Harvey's picture

holly leaf

Hmmm, I'm going to retract this one as well. It was the only sign of 'leaf-mining' on this particular holly bush, and I'm not 100% sure it was a native/wild holly. I should have checked it more carefully, enthusiasm for the mini-bioblitz event carried me away I think!

Thanks for checking it Robert.

----
Entomologist and biological recorder

RHoman's picture

Re: holly leaf

Don't throw the baby out with the bath water! There might be something in the ilicis ID after all. I found a very similar blemish on a garden hedgerow holly today, i.e. a pale greyish area towards the centre (less extensive than the Bristol example), a surrounding darker, brown area (more extensive than the Bristol example) and an outer yellowish ring. Opening up the blemish revealed a fly pupa with a dead, more or less fully developed fly inside. This means a mine must have formed last winter and approached its final stage in April/May 2010. Across the greyish area were a number of very small black pustules, some of which extended into or were to be found on the underside of the upperside of the mine. A bit of digging produced the following:

http://www.bioinfo.org.uk/html/t163427.htm

and

http://www.cybertruffle.org.uk/cyberliber/01209/0304.htm

There is then a strong possibility that the blemish is associated with Phytomyza ilicis , together with a fungus. I am not sure whether the fungus causes the death of the fly or is just an associate of the mine. Perhaps an expert on micro-fungi could throw a bit of light on this one.

Robert Homan