My two year old variegated poplar has been totally destroyed this year by puss moth caterpillars.what little foliage is left is all burnt by the acid they secrete.How do I get rid of them,I’m not a fan of pesticides,and are they likely to return every year?I had planned on planting more of the same,but am now wary as it would be a waste of time and money if they are going to be destroyed every year by these caterpillars.Would appreciate any advice you would have?