Name: Zombie caterpillars.

Age: Not very old, and dead before their time, after a tragic life in which their bodies were taken over by a malign force.

Appearance: Gruesome. A small, liquefied globule of pus.

Sounds like my brother. I see the family resemblance.

It’s a film by that guy who died recently, isn’t it? George A Romero?

That’s it. Dawn of the Zombie Caterpillars, Curse of the Zombie Caterpillars, Return of the Zombie Caterpillars, a franchise with legs. I am sure Hollywood will get round to making those films, but at the moment zombie caterpillars are real.

No way. What’s their problem? They have had the misfortune to be infected by a microorganism called baculovirus, which causes them to eat incessantly, leave their bolt-holes under leaves to climb towards the light and explode, showering other caterpillars in the tree or bush below with the infection.

Why “zombie”? The naturalist who observed the phenomenon among caterpillars of the oak eggar moth species, Dr Chris Miller from the Lancashire Wildlife Trust, described it as “like a zombie horror film” because once a caterpillar is infected it is no longer in control of its actions.

Where did he observe it? I want to cross the location off my picnic-spot list. The Winmarleigh Moss nature reserve north-west of Garstang in Lancashire.

There is no chance of humans getting the infection, is there? Not as far as we know, but that won’t stop the scare stories.

Maybe this is just a Lancashire thing. No, it has been observed before. In fact, some scientists reckon there is an upside.

An upside to caterpillars becoming zombies, exploding and spreading the virus to lots of other caterpillars? Yes.

Do go on. It keeps down the number of moths, which if they are too abundant can strip trees and bushes of their vegetation. Scientists in the US suggest that baculovirus exercises a natural check on caterpillar and moth population growth.

So it’s a good thing? Yes, unless you are a zombified caterpillar.

Do say: Anything you like. The caterpillar is in no state to respond.

Don’t say: “What if it cross-mutates with bird flu?”