Even though no wolves have prowled the English countryside for close on 500 years, deer are believed to have a memory chord in their genes which sounds a warning when they see the green glow.
Two hundred of the reflectors have been set up along a busy one-and-a- half mile stretch of road in the Forest of Dean where scores of deer are killed every year after being hit by vehicles.
The plastic reflectors, designed by an Austrian company, are on posts along both sides of the B4226 near Cinderford. They are set at an angle to pick up car headlights and deflect the beam into the forest.
Forestry experts claim they should cause the deer to hesitate and not attempt to cross the road until the vehicle has passed.
Red reflectors have been used previously in a small-scale experiment . But the new devices beam out a blue-green colour which the makers believe is closer to the sort of reflection a real wolf's eyes would give.
Wildlife ranger Eric Pritchard, who has been patrolling the Forest of Dean and watching over the 500-strong herd of fallow deer for more than 30 years, says: "Between 30 and 40 are killed every year on the roads.
"We want to see if these wolf's eyes reduce the number of deaths. Half of them give a red glow and the others give out the blue-green light. We want to compare them to see which works best.
"I realise these deer have never seen a wolf, or the glow of its eyes in the dark, but we think there's some instinct that has been passed down the generations. They've inherited some instinct from when there were wolves about and they used to prey on deer.
"Ordinary white lights don't seem to affect them. But these coloured glowing lights represent a danger. It's too early to say if the reflectors will reduce the number of deer killed on the Forest roads as we've only just started the trials, but we're hopeful."
The wolf's eye experiment is being closely monitored by the research department of the Forestry Authority, based at Alice Holt in Hampshire.
If it works, reflectors will be installed in other forests where deer cause accidents by wandering on to roads.
A scientist in the woodland ecology branch of Forest Research, Harry Pepper, said: "There have been trials with reflectors of different colours in Germany and the USA. The red reflectors were found to be an improvement on ordinary white light, and we're hoping the green eyes will be even better. I have to say I've never seen the colour of a reflection from a real wolf's eye. But it's how the deer perceive it that's important."
According to the Handbook of British Mammals, wolves survived in England until around 1500, in Scotland until 1740, and in Ireland until 1770.Reuse content