Holes in Rose Leaves

I have two climbing roses Malvern Hills, but only one has developed varying size holes in nearly all of the leaves.  These are contained within the leaf, i.e. with the edge of the leaf intact.  There appears to be no sign of the culprit in spite of regular close inspection.

Any ideas for dealing with the problem (or leaving well alone) would be gratefully received.

Many thanks, Lorraine

It is  most probably caused by Roseslugs which are larvae of Rose Sawflies. I found this for you:  http://www.sactorose.org/ipm/84rosesawflies.htm

They also explain how to get rid of these blighters. Hopefully that will do the trick. 

Hmm, I tried the link myself and it doesn't work. Well, in that case google sactorose and you'll find a link to rose pests and diseases. You'll find the article there. Sorry for the inconvenience.

I will have a look - thank you v.much.