The glow worm

David Chapman / 14 July 2011

Glow worms really are intriguing creatures and it is well worth having a look in your garden at night to see if you have any as garden guests.

Dry and relatively warm springs provided ideal conditions for glow worms so there are many more sightings than usual when the conditions are right.

The glow-worm, Lampyris noctiluca, isn’t actually a worm at all; it is in fact a type of beetle. For the majority of its life span the glow worm exists as a larva which has a segmented body, a little like a centipede, but which has only six legs at the front of its body.

The diet of a glow-worm larva consists entirely of snails, so they are useful insects to have in the garden. Once the larva reaches maturity it stops eating. Adult males have wings whilst females are flightless so it is the females which glow in order to attract a mate.

The astonishing ability of the female glow worm to emit a bright green light comes about through a chemical reaction inside her abdomen, a process known as bioluminescence. The light is generated when a chemical compound known as luciferin combines with oxygen. To act as a catalyst in this reaction the glow-worm uses an enzyme known as luciferase.

Look carefully at a glowing female glow-worm and you will see that the light is emitted from underneath the final segments of the abdomen. In order to show off her light to best effect the female will climb in the vegetation and arch her body so that the underside of her tail-end is pointing upwards.

Once an adult female glow-worm has mated she stops glowing. She subsequently lays eggs and will die within a few days. The eggs will take a few weeks to hatch and the life cycle will therefore continue.

Glow-worms live in a variety of habitats including dunes; roadside verges; gardens; hedgerows; railway embankments; woodland rides and heathland. They tend to glow only when it is completely dark so if you are looking for them in your garden make sure you don’t have any patio lights turned on. The peak season for glow-worms is from June to early August, so don’t leave it too long if you want to see one.

Where to see glow worms

Glow-worms can be found all over the UK but they are quite localised. Good details about their distribution in all counties can be found on the website:

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