Caterpillars are eating my willow!
I have a potted kilmarnock willow which I have had for about 10 years. I recently noticed that a lot of the leaves were turning brown or getting holes in them. On closer inspection I have found tiny green caterpillars eating the leaves. I do not know the type of caterpillar - it is less than a centimetre long, light green, with a yellow line along the underside, the head is black with a yellow band behind it. Looking onlne it could be a Dolerus Ferrugatus
Any advise on how to get rid of this caterpillar as safely as possible please.