Ghostly look for cherry trees
THEY are the “ghostly” forests of cobwebbed trees whose spectre haunts woodlands throughout Europe.
Now the sinister sight of cherry trees draped in eerie webs is taking hold in Scotland after the Beast From The East Siberian storm and recent heatwave created perfect conditions for the phenomenon.
Huge numbers of bird cherry ermine moth caterpillars have created the spectre in woodlands across the country as they spin elaborate webs to protect them from predators.
They feed on bird cherry trees, which are found across Europe, and when they emerge fully grown, they become distinctive white moths with five rows of black dots.
The larvae, which are about an inch long, make large communal silvery webs for protection and then feast on the surrounding leaves, stripping the trees bare.
There are eight species of ermine moths in this country and 2,400 species of moths in the British Isles and they usually pupate into adult moths in July or August. George Anderson, of the Woodland Trust Scotland, said: “Every few years this species explodes in numbers and they strip the host tree of its leaves.
“Trees normally recover the following year so it is not as drastic as it looks.
“It does look very sinister as they drape entire trees in their silk”.
The Trust has been receiving many reports of the ghostly looking trees in recent days, with worried observers expressing alarm at the sight of them being stripped.
It has taken calls about outbreaks at Formonthills in Glenrothes and at its own Geordie’s Wood at Glen Devon with the species enjoying a bumper year across many parts of the country.
The bird cherry moth, Latin name Yponomeuta evonymella, has a maximum wingspan of less than an inch and is found all over Europe.
But when it comes to spinning elaborate webs, no creature can match the power of ermine moth caterpillars. The behaviour is called “tenting” and only some species are able to manage it.
By working together, they are able to conceal themselves in a protective blanket that works like a giant invisibility cloak, confusing birds and other predators.
As the ermines move from tree to tree, they have to cover their tracks and so they keep their protection with them. Over time everything in their path, from cars, to street signs, to grass, becomes shrouded in white, a scene which has been nicknamed the “walk of ghosts”.
One theory suggests that the super-webs form when multiple females lay their eggs on the same plant in areas where food is scarce, such as housing developments.
Other experts suggest that climate change is having an impact as the eggs do better over warm and damp winters.
Experts believe the storm that swept in from Siberia earlier this year, and was followed shortly after by a prolonged heatwave, has provided perfect conditions for the moths, while killing off their parasitic predators.
Tom Prescott, senior conservation officer at Butterfly Conservation Scotland, said: “They are targeted by parasitic wasps and flies who enter their bodies and hatch out when the moths should and kill them off. It’s why they make this incredible web, they hope to keep the parasites and predators out.
“We don’t know for sure but the cold spell could have hit the parasites numbers while the recent warm spell has made it great for the caterpillars, one minute it was grey and overcast and the spring and summer both seemed to appear at once.”
It does look sinister as they drape entire trees in their silk