Having a lot of shrubs, bushes and trees of the same age is an unnatural situation; you would not find it in the wild even after a fire as some trees would survive and a succession of different plants would establish themselves over time. All of this plants would be of local provenance, closely related to the ones that had gone.
On a new estate the developers buy in large quantities of plants from a wholesaler and there is no telling where they come from, but a lot of nurseries are in Holland. You may remember that with ash-die back English ash trees from native seed were grown-on in Holland and then re-imported. At Love's Farm the trees all seem very healthy but they arrived with a lot of passengers in the form of caterpillars.
Barry Dickerson, the County Recorder for Lepidoptera (butterflies and moths), tells me that the brown-tailed moth is well known in southern Britain but has not been recorded in Cambridgeshire more than half a dozen times. That's why we assume that the caterpillars came in with the plantings.
Last summer, Barry and I made separate visits to the estate after residents reported baggy cobwebs on the bushes around their houses. We both found them, but no in huge numbers. On my route I found that most of the bags were on spindle trees and that the caterpillars were those of the harmless Spindle Ermine moth. Barry found much the same at his end of the site.
What is the problem? Brown-tailed moths are very attractive and so are the caterpillars which are covered in hairs to keep them warm and to stop birds from eating them. The hairs break off very easily and can be cause a rash, sore eyes or even a lung infection if you inhale a lot of them so having many thousands of hairy caterpillars in the hedge around your house, at child-height, is not something you would want.
People kept on reporting the problem in the autumn and the District Council's Green-space Team (which includes Countryside Rangers like me) decided to take action. On Thursday this week, a small team of us, led by Barry Dickerson, set out to eradicate the caterpillars once and for all. At first glance this seemed possible but we soon found that almost every tree and bush had one or two little knots of old leaves and cobwebs at the end of the twigs. Barry explained that being out on the thinnest twigs meant that mice would find it hard to get at them. Some of the taller trees had dozens of bags at the top, but most of these were in private gardens where we could not go.
Using loppers and secateurs, we removed a sack full each and these were burned the same day. We obviously need to go back in force and house owners need to be encouraged to eradicate the pitches from their gardens, while the caterpillars are inactive and before the leaves hide them.