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The Society for the study of flies (Diptera)

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#1 2017-12-15 12:59:08

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Are these pustules and mines caused by diptera lavae?

I am of course not sure if I'm taking the correct option in assuming it's diptera larvae that are the cause.

These are on holly leaves. Typically the pustules (they remind me of tiny version of the Silk-button gall) range from about 0.2 to 1 mm across. So the mines are several mm long. I naively assumed that it had to be the Holly Leaf-miner - Phytomyza ilicis.  No explanation for the small green pustules is offered...

However, looking on the ukflymines web site for this species, the upper surface appearance may look okay, but there are no images like mine on the underside, nor anywhere else. So I reason it cannot be that, even though I have seen elsewhere that if you see mines in a holly leaf, it has to be that.  Dead end!

Any polite suggestions!

Nigel G.


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#2 2017-12-15 18:12:12

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 731

Re: Are these pustules and mines caused by diptera lavae?

No, I don't think these are mines. They appear to me to be of fungal origin - perhaps one of the rusts, though I'm not getting anywhere trying to put a name to them. There is something called Puccinia ilicis, described in 1977, but I haven't got access to its description, and can't find anything helpful about it on-line. There are plenty of fungi that affect dead or dying holly leaves, but seldom living ones.
The other possiblity is that these are scar tissue caused by feeding of some other insect (Hemiptera or Lepidoptera?). If they are fungal, you should be able to find spores. If scar tissue, then no spores.

Last edited by Tony Irwin (2017-12-15 18:40:31)

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#3 2017-12-15 19:26:12

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

Thanks very much for those insights and possibilities, Tony.
That gives me several avenues to explore.

Having just been out checking holly leaves elsewhere, I had no trouble finding the indicators of the Holly Leaf-miner, and that looked nothing like mine on the upper surface anyway. (and since there are no NBN records in my 10 km square, I shall log those on iRecord anyway).

It looks to be worth following up because I know I can source further leaves if necessary.

Nigel G.

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#4 2017-12-16 16:31:12

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

I have now found a reference to Puccinia ilicis in Ilex spp, at

https://english.nvwa.nl/topics/pest-rep … etherlands

But no useful description, or images, or references that look hopeful. I am now trying the British Mycological Society.

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#5 2017-12-19 19:10:05

Alan Outen
DF Members
Name: Alan Outen
Registered: 2010-06-24
Posts: 828

Re: Are these pustules and mines caused by diptera lavae?

This is definitely not a rust fungus, nor any of the other microfungi which affect Holly. I think Tony's suggestion of scar tissue caused by insect grazing is the most plausible explanation.

Best wishes

Alan

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#6 2017-12-19 19:31:26

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

I agree, Alan.

I have had a lot of response from the British Mycological Society, and the crusty excavations and lines on the leaf undersides are not recognised at all.

Having now collected some more leaves from holly trees, I have found trails and tangles of silk thread, and what looks like scattered bits of flass. I have also found attached to a leaf underside a small pile of green shiny, torpedo-like objects. At X45, I can't make out exactly what they are, but suspect that whatever is inside these capsules is the culprit!

I am investigating further ... I haven't given up yet.

Nigel

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#7 2017-12-19 21:02:35

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 731

Re: Are these pustules and mines caused by diptera lavae?

Great to have a little Christmas whodunnit mystery!

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#8 2017-12-19 21:47:14

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

It's a pity we don't have the facility to reply with little Facebook emoticons!

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#9 2017-12-19 23:41:06

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 731

Re: Are these pustules and mines caused by diptera lavae?

smile

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#10 2017-12-20 01:34:07

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

Whatever that was, it was lost in translation.
(I'm using Windows 7, and Firefox web browser)

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#11 2017-12-20 14:03:37

KenMerrifield
Administrator
Name: Ken Merrifield
Registered: 2008-02-21
Posts: 238

Re: Are these pustules and mines caused by diptera lavae?

The emoticon appeared for me using the same system.
When posting there is a link 'Smilies' ON or OFF.
I do not know if it also controls if you see them, or if that is set elsewhere.

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#12 2017-12-20 16:30:58

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

I am finding this a bit of a puzzle (as if there isn't enough of them!)
If I put
smile           (that's how Tony's appeared to me)
I am assuming nobody can see my smilie. They appear to be set on by default, and I don't check the box that disables them either.
I did a preview, and there was no smilie. I don't get it.

Bah humbug!

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#13 2017-12-20 19:33:16

AliCullaloe
DF Members
Name: Ali Shuttleworth
From: Fife, VC85
Registered: 2014-08-20
Posts: 78
Website

Re: Are these pustules and mines caused by diptera lavae?

For what it's worth I can see the smiley

Though I don't recognise the leaf damage!

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#14 2017-12-20 23:14:39

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 731

Re: Are these pustules and mines caused by diptera lavae?

Strange - maybe a Firefox thing - I'm on Windows 7 and Chrome, and yours is a very happy smiley, Nigel!

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#15 2017-12-20 23:30:09

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

I've found the answer, but unfortunately not about the holly leaf damage.

I looked on my DF -> Profile -> Display, and then checked the box for displaying graphic symbols.

smilesmilesmile

So that's how you do it!

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#16 2018-01-03 10:09:46

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 973

Re: Are these pustules and mines caused by diptera lavae?

As a final update on this puzzle, that National Agromyzidae Recording Scheme Organiser has had a look at some sample leaves, and can't find a reason for the damage to the leaves.

So I shall have to look again in the spring (and summer, no doubt) for further clues, or any possibilities of something newly burrowing. It must be a species of some sort!

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