There are glow worms in the Garden which are
readily accessible for all to visit and enjoy.
It was from specimens found in the Garden that
the species was formally described.
There is no need to go many
miles to the likes of the Waitomo Caves when
there is a great display at your back door. Glow
worms are widely distributed in this country,
and can be found on damp sheltered banks, caves
etc. in many places in New Zealand.
Glow Worms have been studied in the Wellington
Botanic Garden since the end of the 19th Century.
Early entomologists believed the NZ Glow worm was
a relative of the European firefly. Interestingly,
the European firefly is not a fly, but a beetle.
The name game is further confused when it is
appreciated the NZ glow worm is not a worm, - but
The scientific name of the New Zealand glow worm
is Arachnocampa luminosa, a crude
translation being 'glowing spider bug'. The
reference to spiders is in regard to their 'spider
web' snares produced by the larvae.
The Maori have named these insects 'titiwai'
meaning 'projected over water', which
describes their general habitat along streams. The
name 'pura toke' is also used, meaning 'one
eyed worm' or 'blind worm' .
The European settlers found the glow worms when
they arrived in the country and were immediately
fascinated with them. The earliest published
reports were of insects found in drives in the
The true nature of these insects was first
described by a young 18 year old English man
George Vernon Hudson, living in Karori Wellington,
only a short distance from the Garden. On arrival
in Wellington he commenced studying them, and in
1886 said they were the larva of a two winged fly,
a 'fungus gnat'. He had studied them along the
Garden's Puketea Stream since arriving to
Wellington in 1883. In conjunction with Albert
Norris they were able to unravel the life history
over the next 10 years. Hudson spent in total some
60 years studying and writing about them and other
insects in this country while working for the Post
worm adult fly
George V. Hudson 1890
The Glow Worm adults live for a short time only;
1-2 days for the female and 3-5 days days for the
male. The adults cannot eat, only the larvae being
able to ingest food. The adult is slightly larger
than the mosquito, about 15 mm long. The 'self
adhesive' eggs are laid in clusters of 30-40 on
banks and in crevices, each female laying on
average 130 whitish eggs which darken with age.
They are some 0.75 mm in diameter and hatch in
about 3 weeks.
On emerging, the larvae light up immediately, and
are the stage of the insect that most people will
see. They are about 3-5 mm long, and grow over the
next 6 to 9 months to 30 mm long, the length of a
match stick. In caves with a more assured food
supply they can grow to 40 mm long. The larva is
the only stage that feeds on small insects, midges
and flies, and even other glow-worms. There are 5
instars; the larvae molts 4 times during this
worms in garden
Glow worm habitat lit
worm home on bank
At night it is difficult to appreciate their
homes, but with a torch you can see the
interesting structures they have built. They form
a horizontal suspended tube of silk and mucus from
which they suspend their silk fishing lines, with
droplets of a sticky mucus to catch small gnats
and flies, attracted by the glowing lights. These
lines can be up to 50 cm long in protected caves,
but in the Gardens are normally some 20 to 50 mm
long because of the wind. The lines are coated
with globules of sticky mucus which traps any
insects that comes into contact with it. It is
thought the globules also contain a paralyzing
chemical to stop the trapped insect struggling and
causing damage to the snare.
The larvae pupate for about 12 days. Both the pupa
and adult are able to continue glowing. The pupa
is transparent, and is some 12-15 mm long. The
female in the pupa can glow very brightly during
the last 2-3 days before emerging to attract
males. A number of males are often seen on the
pupa awaiting the female to emerge, mating of
ten occurs immediately the
female emerges. During this time the male flies
around in search of the female, who produces the
brightest light to attract them. On emerging from
the pupa the adults move around the habitat, but
neither are strong flyers, the weighty female
carrying her load of eggs can travel short
George V Hudson 1890
The brightness of the lights can vary,. When the
insect is hungry it will generally glow more
brightly. Females in the pupa can glow very
brightly, and also female adults, in both cases to
attract mates. Occasionally two larvae will fight
over space, and will glow very brightly in an
attempt to assert their dominance.
Larvae in particular are terrestrial, and will
fight if they believe their space is invaded.
Often the looser will be the winners dinner. This
territorial display results in the insects being
quite evenly distributed in colonies, a feature
which is readily apparent when you look at their
display of glowing lights.
The light emitted by the insect is
bioluminencence, the result of a chemical reaction
that involves several components- luciferin a
waste product, luciferase an enzyme that acts on
luciferin, and ATP (adenosine triphosphate), an
energy molecule, and oxygen. These combined form
an electronically excited product capable of
of glow worm
+ LICIFERASE +ATP + OXYGEN
EXCITED PRODUCT + LICIFERASE
You will see plenty of larvae. You may see some
pupa, especially from April to July, but adults,
because they are so small and short lived, are
rarely seen unless caught in a snare or spiders
web. In caves the greatest number of larvae have
been identified from October to February, and
this seasonality is likely to exist in the
Garden. Glow worm colonies are found over quite
extensive areas in the Wellington Botanic
Garden. George Hudson noted that the best
displays were seen under humid conditions with a
light north west wind.
|Glow worm trap in the
Wellington Botanic Garden
When George Hudson studied
the insects in the 1880's, he had to wade up the
bed of the Puketea Stream, at the bottom of a
steep gully. Subsequent development of the
Garden has cut paths into the hills creating
banks, many with overhanging areas along which
the glow worms have found attractive to live.
They are now present in considerable numbers,
and can be easily seen from those paths in two
main areas within the Garden.
George V. Hudson 1890
The three drawings are
from G.V. Hudson's
original article on Glow worms published
The Transactions of the NZ
The Glow worm Arachnocampa luminosa is
unique to New Zealand, although 3 similar
species are found in Australia, in Tasmania, New
South Wales and Queensland . There are also
reports of another species in Fiji.
If you look for
them don't make too much noise, or shine
torches on them too much, or they will go out.
Please do not touch or remove, as they cannot
survive away from their natural habitat.
FOR DETAILS OF GLOW WORM
TOURS CLICK HERE
Information on these fascinating and
spectacular insects can be seen on an Australian