1 HOW AND WHY DO GLOWWORMS CREATE LIGHT? Glow-worms are actually beetles, found in species-rich meadows and grassland across much of the UK. Only the adult females glow, to attract the flying males. The yellow-green light – produced by mixing two chemicals, luciferin and luciferase – is beamed out of the final segment of a female’s abdomen during evenings in June and July. 2 CAN YOU GET GOOD AND BAD GLOW-WORM YEARS? Yes. A combination of circumstances (that are still not fully understood), can lead to boom years at certain sites. Glowworms typically spend two years in larval form, hunting snails and slugs that they paralyse with a toxic bite. Damp years, when their mollusc prey is plentiful, can help to boost numbers of glowing adult females the following summer. Glow-worms only feed as larvae; the adults have no mouthparts. For the three or so weeks that they survive in adult form, all energy goes into mating. 3 HOW LONG DOES THE GLOW LAST? Glow-worms usually spend the day hiding in crevices under logs or stones. Females emerge each night and glow for a few hours, often climbing grass stems to make themselves more visible, until they attract a mate. This could happen immediately or take days. Once mating begins, a female turns off her light and descends, taking her partner with her. She will lay up to 100 eggs within a day or so, but dies before they hatch, about a month later.
Robin Scagell O glowworms.org.uk