By Sarah Mukherjee
Environment correspondent, BBC News
Sherwood Forest's historic oaks are being closely watched by rangers
The UK's most famous woodland, Sherwood Forest, faces the prospect of being invaded by two moth species, which could prove fatal for its historic oak trees.
Rangers at the Nottinghamshire National Natural Reserve are being extra vigilant, looking out for tell-tale signs of the moths' arrival.
The outlaws are the oak processionary moth, which is already establishing itself in South-East England, and the brown tail moth that is moving southwards from Yorkshire.
Sherwood used to cover 100,000 acres (40,500Ha) and was a hunting ground for Plantagenet kings. Only a fraction of that now remains, but under a blue-gold late summer sky, the green foliage of oak and birch still looks stunning.
Spraying for solutions
You have to be careful when talking about Robin of Loxley, as Robin Hood is sometimes known, as many regions in the country claim him, but it's fair to say Sherwood is traditionally considered his home.
But if he and his band of merry men were riding through this particular glen, bows and arrows would do little to see off the modern threat to his manor - but hairspray might just do the trick.
Sounds like something from Monty Python, but it is, in fact, sound science. Both of the tiny modern-day aggressors are covered in short, toxic hairs that can cause severe skin irritations.
The only way to stop them shedding is to blast them with hairspray.
"We haven't got them yet, but we're looking very carefully indeed for any signs," says Sherwood's chief ranger Izzie Banton.
"They can do real damage to the trees, and stopping them is an expert's job. We have an incredibly special forest, and even losing one tree upsets me."
A squirt of hair spray could halt the spread of brown tail caterpillars
Over the centuries, Sherwood Forest has given up its arboreal bounty to build some of our greatest monuments, such as Lincoln cathedral, as well as to fashion the ships that defined and mapped an empire.
Even now, conservationists say that Sherwood has the largest collection of ancient oaks in Europe and is a unique natural resource.
But the species threatening the trees could do more damage then any of the axes of yore.
The oak processionary moth is native to the Mediterranean, but its range is extending, perhaps because of climate change. Its caterpillars mass in writhing clumps, stripping oak leaves.
And wildlife experts in Yorkshire have been using pheromones to attract male brown tail moths to other males, in an attempt to reduce their numbers.
Experts there say they won't know whether it has been successful until next spring, when the caterpillars come out.
But they say finding environmentally friendly solutions to control invasive species that will not harm native animals is a real headache.
Izzie Benton agrees: "Recently, we've discovered two species of native moth in the forest and we want to do what we can to protect them but, at the same time, we want to stop the invaders."
As we walk through the forest, I point to a small moth settling on one of the oak trees. Izzy looks alarmed, and then relaxes. "Too small", she murmurs.
She no doubt hopes that's as close as she's going to come to a moth invasion.