Latin name: Lampyris noctiluca

Size: Approximately 15mm long

Distribution: Found in parts of south and mid England, lowland Scotland and Wales.

Months seen: Active from May to late August.  They are most noticeable at night in June and July when the females light up to attract the males.

Habitat: Low growing vegetation.  During the day they can be found under stones and logs.

Food: The larvae feed on small snails and slugs.  The adults rarely feed at all

Special features: The glow-worm is not really a worm at all.  In fact it's a beetle.  This is most obvious when you see the male.  The male is about 12mm long, and is a light brown colour.  He's equipped with large, light-sensitive eyes which he uses for scanning for glowing females.  Males have a weak fluttering flight, similar to moths.

The larvae look like a cross between a caterpillar and a millipede.  They're about 25mm long and have a soft, rubbery bodies.  The tail is equipped with a series of white bristles which is used to remove slime from its body after eating snails.

The female is the one noticed by most people since she produces a green light from her bottom.  It's about as bright as an LED, like those on electronic gadgets.  It is a cold light, so no energy is wasted in heat production.  The light is created by a substance in the abdomen called luciferin, which when mixed with oxygen, breaks down creating the light.

Only the last few segments of the females abdomen emits light.  She has complete control over the light emission, and is able to switch it on and off at will.

The larvae also emit light, but from a smaller patch, and even the eggs of the glow-worm, which are laid in clusters of up to 100, can emit light.

The adult beetles only survive for a few weeks, and in that time need to mate and lay eggs to ensure the survival of the next generation.  All this depends on the low-flying male spotting the glowing female and mating successfully.

Street lighting and security lighting seems to have a detrimental effect on glow-worm reproduction.  In areas where there is artificial lighting, males are attracted to this, and miss the females altogether.  For this reason, glow-worm populations seem to survive better in areas with less 'light pollution'.

The best time to look for glow-worms is after 10pm when it's dark.

If you see any glow-worms please fill in the Glow-worm Sighting Form

Related Pages

• UK Safari Glow-Worm Section
• UK Safari Creepy-Crawlies Section