My cousin who lives on Bredon Hill walked Anna and I (and his black labrador!) up the hill at 8:30pm or so on saturday night, to try and spot a few badgers which live in the wood near the top of the hill, and to locate some Glow worms, which he told us were glowing magnificently, in large numbers, at a spot halfway down Bredon Hill.
Of course, we saw no badgers (though the dog chased after one in the gloom we think) but we DID see Glow worms!
As my cousin quite rightly remarked, Glow worms are creatures of high summer - june and july really, and he had seen many "worms" last summer at least (when we did have a summer, remember?)!
September is a little late for the adults at least, but we were most chuffed, when the light finally went, the cloud lifted to show us the very bright stars (and satellites!) and about a dozen or so (that we could find, anyway) Glow worm larvae switched their very faint lights on and off in the long grass.
We couldn't work out why the glow wasn't constant and bright (my cousin and I had only seen brighter, more constantly glowing Glow worms, in the height of summer before) , but after a little research, I've since discovered that the adults only live for a short period of time, and after the female mates and lays eggs (it is ONLY the female Glow worm that glows), she switches off her light and dies.
The larvae soon hatch and rumage around the grass, feeding on snails (the adults never feed - which explains the short lifespan of an adult Glow worm!), flicking on and off its MUCH duller abdominal light than the adult females - but you'll have to hunt for them, like we did!
For your information, Glow worms are BEETLES (not worms) although the larvae (and females, a bit) look a little like fat caterpillars.
The glow comes about by a process known as Bioluminescence - a cold light and in the case of a Glow worm, an almost electric green colour, about as bright as an LED or cigarette end. The chemical used to form this light is known as LUCIFERIN. Those of you that know your ancient languages, will know that LUCIS (LUX) and FERRE in Latin mean light and carry respectively. Lucifer (as well as the "fallen angel, associated with Satan") always did mean "Light bringer or carrier".
The luciferin in the Glow worm's abdomen, oxidises (using an enzyme (Luciferase I think), and as it oxidises, the green glow is emitted - a wonderful sight if you care to look.
I know of two sights in the Chiltern Hills, where I used to go and look at Glow worms - one in a graveyard in the centre of a large town, and I'll always marvel at these little beetles...
A wonderful evening, on a beautiful hill in the Cotswolds..., and we hope to return next summer to see the hundreds of adults glowing on the hill!
NB. The photo is not mine, and shows an adult female, not a larva.