But both this and the less spectacular light produced by males and larvae are thought to serve a defensive purpose, by scaring off possible attackers. The glow of the female is primarily a mating signal. They inject into them a fluid which paralyses them, and reduces their inner flesh to liquid, which the larvae are then able to draw off as food. The glow-worm’s larvae, which also glow, are voracious carnivores, their chief source of food being slugs and snails. It has only a dull glow, but it has large, sensitive eyes which enable it readily to detect the light of a possible mate. This is dark brown in colour, and slightly smaller than the female. The main purpose of the light is to attract the winged male beetle. The fact that it somewhat resembles a larva accounts for its being called a worm. The female is between 15 and 20 millimetres in length, and is wingless. In the case of Lampyris noctiluca, it is the brownish-grey female which provides the bright light. The emission of light is controlled by the insect’s nervous system, and takes place only in the hours of darkness. The light is generated chemically in special cells, which have to be abundantly fed with oxygen. ![]() ![]() The process of light-production in glow-worms and fireflies is known as “bioluminescence”. The glow produced by such insects is generally greenish or yellow, though the “railroad worm”, a beetle of South America, has not only rows of green lights along its body, but also a red “headlight” on its head. But these are not scientific names, and are applied to many luminous insects, both beetles and other types. In general the term glow-worm has come to be used of those which emit a continuous light, while those which give out a series of flashes are called fireflies. Some are called glow-worms, others fireflies. The common glow-worm, Lampyris noctiluca, belongs to the same family as a number of other luminous beetles. ![]() This is the greenish-yellow display of glow-worms, gleaming like fairy-lights along a hedge-bottom, or in a garden.Īs with so many small creatures, the common glow-worm of Britain and Northern Europe was given its name long before close study by entomologists revealed what it really was. Summer offers plenty of fascinating sights in the countryside and one of the most enchanting is to be seen not by day, but at night.
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