The moth, whose tiny hairs are an irritant to humans and animals, is now moving out beyond the M25 towards RHS Wisley and has also been found in Windsor, he said. "It's potentially a real problem. We have to tighten biosecurity around letting things in." He gave the example of the related pine processionary moth, currently spreading northwards in continental Europe, and the highly destructive emerald ash borer. "After 23 June there will be some changes whichever way the referendum goes," he added.
He said of the Hive structure, currently being installed in the garden (HW, 29 January): "We can go on about the importance of pollinators but this will give us a captive audience to get that message across. It could bring us up from 1.5 million to two million visitors this year." But he warned: "I don't see the next generation of gardeners and arboriculturists coming through. We will hit a problem in the next 10 years. We need to inspire them. Our schools aren't doing that."
Within the west London botanic garden "there's a 200-year-old law here that says you can't climb the trees", he pointed out. "But if I see a child halfway up one I tell them they should go into arb." A log trail made from trees brought down in recent storms has proved highly popular, he added. "That's where we will get the next generation."