The glow worm, Lampyris noctiluca, is actually a beetle in the insect family Lampyridae meaning "shining ones" in Greek. This family also includes other glowing species. Although Lampyris noctiluca is often referred to as a glow worm, it isn't worm-like at all. Other names that you may have heard for the Lampyridae family in general are fireflies and lightning bugs. Lampyris noctiluca is usually brownish to blackish in color. The adult female is 12-20 mm long, while the males are much smaller. The larvae are often only a few milimeters long. (Borror & White 1970; Scagell 1994; Tweit 1999)
The males possess two pairs of wings, but use only the second pair for flying. The first pair of wings, the elytra, form a cover over the second pair. The females do not fly. (World Book 1998)
They are soft-bodied and elongated. Their head is concealed from above by a pronotum, and their antennae are threadlike. Only the last few abdominal segments are luminous. (Borror & White 1970)
The adult female is the one responsible for the most active glowing although the larva, which is very similar to the female in respects, also glows. The male may glow slightly but is very different from the female who uses her glowing organs to attract and stimulate the male. Larvae glow much more faintly, and only intermittently, for a few seconds at a time. They are also not worm-like but have segmented bodies and six legs at the head end, quite similar to adults. However, when they help themselves along with their tails, they do appear a bit like caterpillars. (Alliston 1998; Scagell 1994)
Other Physical Features: ectothermic ; bilateral symmetry
They need an open area where the females can display to attract a male in June, July, and August. They retire into the ground during the day. They prefer open grass or hedges to woodland, but rarely are they to be found on land which has been improved for agriculture. (Anonymous 1995)
Adults rarely feed. Despite their diminutive size, the larvae are the fierce predators. They roam leaf litter in search of tiny snails and slugs, which they bite and inject with a neurotoxin that both immobilizes and liquefies its meal. They then suck their prey empty. (Tweit 1999)
Life History and Behavior
To attract the males who are flying at about a meter high, the female finds a plant stalk to climb. When she is clear of most of the vegetation on the ground she bends her abdomen upwards displaying her glowing organs in hope of attracting a passing male. (Alliston 1998)
Each individual female has an adult glowing life of a few weeks until she mates, since she dies soon after laying her eggs. After a few weeks the eggs hatch into larvae, and they remain as larvae for one or two summers, feeding on small snails which they apparently paralyse before sucking them empty. The two or even three-year gap between a mating and the subsequent appearance of an adult helps to explain the characteristic "boom or bust" cycles of glow-worm populations. It's possible to find plenty on a site one year, yet few or none at all the next. (Scagell 1994)
Lampyris noctiluca is the only known example of hormonal influence on sex determination in insects. Sexual differentiation of male and female gonads begins during the fourth larval instar. The differences are subtle at this stage. Male cells in the apical tissue begin to divide during this time, whereas in females it is cells in the basal tissue of the gonads that would divide. When testes were transplanted into females earlier than the fifth instar larvae, they induced a transformation, or a masculinization, in the female recipients. Testes could not produce such effects in female-determinted larvae after late in the fifth instar. Converse experiments did not produce feminization in young males. Hence, ovaries of this species can not feminize males, but testes can transform ovaries of pre-fifth instar females into testes. (Stanley 1997)
Molecular Biology and Genetics
Barcode data: Lampyris noctiluca
Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen.
Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Statistics of barcoding coverage: Lampyris noctiluca
Public Records: 1
Specimens with Barcodes: 11
Species With Barcodes: 1
Outdoor lighting may threaten the species survival. Artificial night lighting-from street lights to headlights-may distract fireflies cruising for mates, drowning the insects' signals in excess light. Lamp-free reserves such as sheltered hollows shielded from lighting has been suggested to save Lampyris noctiluca. (Frank 1996; Tweit 1999)
The survival of fireflies depends on the existence of the natural areas in which they breed and live. Populations are declining because of destruction of habitat, especially wetlands. Researchers also speculate that commercial firefly collection for luciferase is also a factor in the decline. (Anonymous 1995; Tweit 1999)
Relevance to Humans and Ecosystems
Dr. Robert Ledley developed a test that can determine within minutes the best treatment for a TB patient. This new test was developed by using the same substance that makes fireflies glow. TB bacteria are injected with a gene that produces luciferase, the same enzyme that helps to illumine fireflies. As long as the bacterium is alive it keeps lighting up, but when it dies the luciferase gene becomes inactive and the light goes out. Therefore, it can be distinguished within minutes which antibiotics douse the TB bacteria's lights and thus will work best against that strain of TB. Previously it took as much as 10 weeks to figure out which strain had infected a patient. (Riordan 1999)
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Lampyris noctiluca, the common glow-worm of Europe (see also "glowworm"), is a firefly species of the genus Lampyris. These are beetles, as evidenced by the hard cases which close over the wings when they are not in use.
Lampyris noctiluca presents a conspicuous sexual dimorphism. The males are winged, with brown elytra, a clearer pronotum and a large brown spot in the middle, while females are larviforme, wings are missing and they are often twice the size of the males (up to 25 millimetres or 1 inch in length).
These beetles use their bioluminescence to attract mates. The adult females are mostly famed for their glow, although all stages of their life cycle are capable of glowing.
In Britain, this species is fairly common compared to its cousin Phosphaenus hemipterus – the lesser glow worm – which is very rare.
The range of this beetle stretches from Portugal and Britain in the west, right across Europe and Asia to China in the east. It also survives further north than any other firefly, almost reaching the Arctic Circle. It is not found in North or South America.
Light production is vital for Lampyris noctiluca. With it they have greater chances of mating, so there is a complex process involved.
They emit yellowish-green light from the translucent underside of their last three abdominal segments to attract the smaller males, which are winged. They will glow for 2 hours and then retreat back into their hiding place until the next night, or stop glowing as soon as they find a mate. The females can survive up to 10 consecutive nights doing this.
The light can be seen by males up to 50 yards away. The light is emitted continuously, although they will wave their abdomens from side to side, which gives the impression of it brightening and dimming. Larvae are sometimes seen to glow, although they seem able to turn off their light more easily than the female, especially when disturbed.
The insect can regulate its light production by controlling the oxygen supply to the light emitting membranes containing luciferin. The chemical reaction producing the light from luciferin is catalysed by luciferase, the exact chemical structure of which is determined by the glow worms individual genetic structure, which in turn determines subtle differences in the light produced from individual to individual. Virtually all of the energy produced is light; only 2% is heat.
The males are sometimes attracted to man-made light fixtures.
The peak glowing period is evenings in June and July.
They are found in old-growth grassland, especially on chalk and limestone soils. They are also found in verges, hedgebanks, and on heaths. The larvae live in sheltered places – under rocks and wood, but do crawl over different terrains.
Once the females have attracted the males with their glow, they mate, lay eggs, and die.
Typically 50–100 are laid over 3 days, the adult not surviving to see them hatch. They are laid in fairly moist places, e.g. stem of grass or under moss.
The eggs are pale yellow, 1 mm across. They may glow faintly yellow and take between 27 and 45 days to hatch depending on the weather (colder=longer).
The eggs hatch after 2 or 3 weeks. Larvae and adult females look similar, however larvae have light spots on each of 12 segments, whereas adult females have a completely black back.
The predatory larvae feed for two or three years on slugs and snails which they inject with a brown toxic digestive fluid, delivered by a series of nips and bites. The poison takes a while to work, and the larva has to be careful not to become stuck to any protective mucus that its prey may secrete. The prey is gradually paralysed and the digestive fluid turns part of it into a brown broth that the larva can lap up. The prey remains alive, and some partially eaten victims have been known to crawl away after the meal.
The slugs and snails are often 200 times the weight of the beetle larva. The larvae are nocturnal, and are most active during moist conditions, when their prey are most active.
The larvae may moult four to five times in their lifetime. They spend their winter under logs, stones, wood holes or leaf litter, their bodies drawn in like concertinas, hibernating as their food source becomes increasingly hard to find. They wake up in spring, and the cycle is repeated for one more year.
They become adults from May to July, eating little, surviving on food reserves built up during its time as a larva, and dying after reproducing.
Threats to species numbers
Threats include habitat destruction, habitat fragmentation, pollution, distraction from artificial lights, insufficient grazing and climate change.
- Hickmott, W; Tyler J. (2011). "Seasonal variation in the female display period of the glow-worm Lampyris noctiluca L. (Coleoptera: Lampyridae)". Lampyrid 1: 14–21.
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