Iris attacked

[tonyg]

I notced what from a distance looked like a rust on the leaves of Iris suaveolens.  Close inspection revealed critters.

What are they please? ... (dont just say little caterpillars!)  They are very tiny, perhaps 2mm long.

I can squash them but the leasions on the leaves look nasty, should I remove all the foliage?

[Lesley Cox]

This is a bearded iris Tony? Sorry I can't help with ID. I've never seen anything like these but given that it's near the end of your growing season for such irises and leaves will be dying back, I'd take a punt and cut them hard back below any sign of the cats or lesions, and BURN the stuff please. Then spray with a systemic insecticide in case there are more lurking in the ground or elsewhere and keep a close eye. I'd give another spray as soon as there's any sign of new growth in the spring as well. Looks nasty!

[Maggi Young]

It could be Iris leaf borer damage, though that sould more likely be earlier in the year. I know that this pest ( a moth0 lays eggs on the leaves which then suffer this kind of damage..but the only pix I can find of the 'bugs' show a much larger ( up to 2 inches, 5cms) caterpillar which is not so dark pink as these little guys you have....kill and burn I think, only remedy.

[Anthony Darby]

I would suggest a sawfly larva. Perhaps Tenthredinidae? Solomon's Seal has a similar pest, but these larvae are black.

[Maggi Young]

Tony's critters are much smaller than the solomans seal sawfly caterpillars, though, aren't they, and they look more squishy and less LIKE caterpillars... Yuck. Hungry little pests, though.

[Anthony Darby]

I still think sawfly. The larvae in this group are often referred to as 'slugs', such as the 'Pear Slug' (Caliroa cerasi). They are not long after hatching, as the little incisions in the leaf indicate - perhaps made by the female's 'saw'.

[Gerdk]

I would suggest a sawfly larva. Perhaps Tenthredinidae? Solomon's Seal has a similar pest, but these larvae are black.

When googling for ' Iris-Blattwespen ' (= Iris sawflies) I came along
Rhadinoceraea micans - Tenthredinidae. There are pics for identification.

Gerd

[Anthony Darby]

That species has big grey larvae Gerd. Haven't been able to find pics of small larvae.

[Gerdk]

That species has big grey larvae Gerd. Haven't been able to find pics of small larvae.

Anthony, me too. This was the reason that I am somewhat reluctant.
So Tony let them grow larger. If you squash them you'll never know what is feeding on your plants.

Gerd

[tonyg]

Ah - too late.  All infected leaves removed.  The rhizomes look strong and healthy so hopefully there will be strong new growth and flowers in spring.  They are special forms - I'll post pics if all goes well.

Many thanks to all who contributed.

[RolloP]

The photo of the Iris leaf and orange maggots is fascinating. The two are not related. The dark lesions on the leaf are rust pustules, probably causes by Puccinia iridis, and the maggots are the larvae of a dipterous aphid predator, probably Aphidoletes aphidimyza. I suspect the the larvae are selectively grazing the Puccinia pustules as a source of food in the absence of their preferred prey. I have seen this before with an other Puccinia sp.on Chysanthemum where an outbreak of Chrysanthemum White Rust was curtailed by slugs selectively grazing the fungus and prevented further spread of the infection.
 Call me a sado, but a brilliant picture !

[Maggi Young]

Hello, Rollo, a very warm welcome to you!
Great to have this information put forward here.

I have seen this before with an other Puccinia sp.on Chysanthemum where an outbreak of Chrysanthemum White Rust was curtailed by slugs selectively grazing the fungus and prevented further spread of the infection.

Fascinating to hear of a case where a pest can actually be a helper, too..... this was news to me.
Thank you for your input... I hope there will be more....

[Lesley Cox]

Hello, Rollo, a very warm welcome to you!
Great to have this information put forward here.

I have seen this before with an other Puccinia sp.on Chysanthemum where an outbreak of Chrysanthemum White Rust was curtailed by slugs selectively grazing the fungus and prevented further spread of the infection.

Fascinating to hear of a case where a pest can actually be a helper, too..... this was news to me.
Thank you for your input... I hope there will be more....

A warm welcome from me too Rollo. I agree about the picture. All natural things - even if not nice - are fascinating to me.  A great pity that probably slugs can't be trained to act in a similar way to many other nasties.

[tonyg]

Welcome and Thanks Rollo
The leaves are now growing again and there are still signs of the rust on some leaves. 
I like the sound of a predator for my aphid collection  I will keep an eye out for them and make sure they find their way into my greenhouse!