Where to look for glow-worms

A night-time safari in the Chilterns can reveal some very special creatures

You would be forgiven for thinking that glow-worms are worms and they glow most of the time. Both of these are false.

Glow-worms are in fact beetles and it is only the adult females that glow brightly. The peak time for finding glowing glow-worms is summer evenings in June and July. The adult females live for just two to three weeks. They’re wingless, and use their glow to attract the winged males.

The chalk grassland of nature reserves such as Grangelands and The Rifle Range on the Chilterns escarpment is a good place to start your search.

Look out for glow-worms as soon as it gets dark. Unlike fireflies which appear to twinkle as they turn their ‘glow’ on and off, glow-worms glow for a couple of hours at a time, turning off their glow after they’ve mated.


Glow-worm by Andy Fairbairn

The beautiful green light that glow-worms emit is a form of bioluminescence, which is a type of chemical reaction within the beetle.

After mating the female will lay her eggs and then dies soon afterwards. The eggs hatch into glow-worm larvae, which live for a year or two feeding on small snails. The larvae pupate in burrows before emerging as adults, which don’t feed at all and simply need to look for another beetle to mate with before the cycle begins again.

The best habitat for glow-worms is also where you will find some of our beautiful wild flowers, including orchids, and insects such as the beautiful chalkhill blue butterfly. You might even spot glow-worm larvae feeding on snails.

Carefully managing nature reserves by cutting back small trees and brambles (known as scrub) is beneficial to a whole host of wildlife such as flowers and small birds. It's especially helpful to the glow-worms because it allows their luminous abdomen to glow brightly and act as a beacon in the countryside.

Artificial lights may have a negative effect on glow-worm populations by attracting males away from the glowing females. Changes in landuse may also affect populations. If land becomes too overgrown the females won’t be seen by the males, and ‘improving’ grassland for agriculture or using pesticides and herbicides will harm the populations too.

If you are lucky enough to see a glow-worm glowing, leave it in peace to attract its mate and start the next generation so the Chilterns can continue to glow for years to come.

Where to look for glow-worms


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