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Fireflies

Source:  Museum of Zoology - Animal Diversity Web - http://animaldiversity.ummz.umich.edu,Written by Melissa Gayton, Southwestern University student

Lampyris noctiluca (European Glow-Worm): NarrativeThe University of Michigan -

Classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Family: Lampyridae
Genus Lampyris
Species: Lampyris noctiluca
Table of Contents
Geographic Range
Physical Characteristics
Natural History
Food Habits
Reproduction
Behavior
Habitat
Economic Importance for Humans
Positive
Conservation
Other Comments
References

^ Geographic Range
Palearctic: In Great Britain, Lampyris noctiluca favors chalky or limestone
areas. It has been found in valleys in Wales and Scotland. (Scagell 1994) The
species occurs elsewhere in Europe, for example in Belgium and Finland.


^ Physical Characteristics
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)


^ Natural History

^ Food Habits
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)


^ Reproduction
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)


^ Behavior
Lampyris noctiluca adults are active at night and spend their days in moist
places under debris. The larvae are also nocturnal and are rarely seen,
however, whenever conditions are right for snails, usually between the months
of April and October, they can be spotted. The adult stage, while short, is
the easiest to spot. They glow for a few hours at a time, and usually stop
glowing soon after mating. The best time to see the insect is between 10 pm
and midnight on dry summer nights (rain tends to make the females shelter
lower to the ground and in thicker vegetation). (Glow Worm Lampyris noctiluca
1993; Scagell 1994)


^ Habitat
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)


^ Economic Importance for Humans

^ Positive
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)


^ Conservation
Status:
IUCN: No special status
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)


^ Other Comments
The light of a firefly is actually cold light, producing very little wasted
heat. Unlike an ordinary incandescent lightbulb, for instace, which transforms
only about 3 percent of electrical energy into light (losing the other 97
percent as heat), firefly light is 90 to 98 percent efficient. Their light is
produced through a chemical reaction that involves three compounds: a small
organic molecule called luciferin (named for the fallen archangel, Lucifer, the
bearer of light); adenosine triphosphate (ATP), a molecule that drives the
synthesis of protein; and the catalyst luciferase. When luciferase is added to
luciferin and ATP in the presence of oxygen, the energy of ATP causes the
luciferin to glow. (Tweit 1999)


The bioluminescent advertisement seems counterproductive, destined to draw
predators such as frogs and birds. New research, however, shows that most
fireflies in every life stage contain potent steroids. So powerful are these
poisons that when thrushes are fed insects painted with an inconspicuos firefly
extract, they promptly vomit up their meals. The glow is indeed an
advertisement, but like the orange color of a monarch butterfly, the light says
"I'm poisonous!" rather than "Eat me!" (Tweit 1999)


Dr. Douglas W. Tallamy, an entomologist at the University of Delaware, offered
mice fireflies and mealworms. All the mice rejected the foul-tasting fireflies
in favor of the mealworms. In addition, the researchers showed that mice had the
ability to associate light with bad tasting tidbits. Dr. Tallamy and his
colleagues concluded that predators equate the firefly larvae's luminescence
with its bitter taste. This study is believed to have been the first
laboratory-based evidence of an insect using bioluminescence to advertise to
predators that it is an untasty meal. (Hsu 1997)


^ References
"Glow Worm Lampyris noctiluca" (On-line), Available
http://www.bracknell-forest.gov.uk/council/departments/leisure/countryside/bap/glow_worm.htm
. (February 19, 2000)
The 1998 World Book Encyclopedia, International Edition. World Book, Inc., .
Alliston, Mark. July 22, 1998. "Glow Worm Lampyris noctiluca" (On-line),
Available http://www.the-timeless-dimension.com/in008.htm . (February 19, 2000)
Anonymous. Mar 1995. Fireflies/Lightining Bugs(Lampyridae). Organic Gardening
42(3):24.
Borror, Donald J., White, Richard E. 1970. Peterson Field Guides: Insects.
Houghton Mifflin Company, Boston.
Frank, Kenneth D. July 1996. "Impact of Outdoor Lighting on Moths" (On-line),
Available http://www.darksky.org/ida/ida_2/info109.html . (February 19, 2000)
Hsu, Karen. July 8, 1997. Survival of Baby Fireflies. New York Times :C5.
Riordan, Teresa. Aug 30, 1999. Researchers marshal more effective weapons in the
battle to contain a tuberculosis resurgence. New York Times :C9.
Scagell, Robin. 1994. "Glow Worm - Lampyris noctiluca" (On-line), Available
http://www.uknature.freeserve.co.uk/glowworm.html . (February 19, 2000)
Stanley, David. 1997. "Entomology 401/801-- Insect Physiology: Home Page"
(On-line), Available http://ianrwww.unl.edu/ianr/entomol/ent801/repro.html .
(February 19, 2000)
Tweit, Susan J. July/Aug 1999. Dance of the Fireflies. Audubon 101(4):26-31.
Reference written by Melissa Gayton, 50-112: Introductory Biology section
3. Edited by Stephanie Fabritius.
Page last updated May 2000.

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