Cover Photo Is of Glowworm Lava and Threads Photo: Malcolm Wood

Rosalie Frederikson

Waitomo Caves Museum Society Inc. P.O. Box 12 Waitomo Caves New Zealand

Cover Photo is of Glowworm Lava and Threads Photo: Malcolm Wood

@ l983 Reprinted 1984 TABLE OF CONTENTS INTRODUCTIOJ

Page A feature of anyone's trip to Waitorco Caves is a visit to the Glowworm Caves, and in the Glowworm Grotto we feast Introduction i our eyes on a wondrous sight. The cavern roof is dotted Early Records of the New Zealand Glowworm 1 with thousands of tiny lights, each being produced by our Habitat 2 New Zealand glowworm.

Life Cycle Our New Zealand glowworm is quite different to so-called 'glowworms' from other parts of the world. These others Egg are mainly luminous beetles which use their lights only Larva to attract the opposite sex. The New Zealand globworm by Pupa > coEtrast is the larval stage of a fly, X-d will use its Adult 6 light in different stages of the life cycle as a lure for focd as well as to attract a mate. Mating 8 The scientific name of the New Zealand gloxworm is Oviposition 9 Arachnocampa luminosa. It be1or.g~to the family MYCETO- The Nest and Fishing Lines I0 PHILIDAE or 'fungus gnats', most of which, as the name Feeding Behaviour 13 suggests, feed on fungus. 'Aracho' refers to the web it spins, 'campa' to its gnb-like qualities and 'lminosa' Bioluminescence 16 to the light it emits. This species is found only in Population Regulation 19 New Zealand, but it has three relatives within the genus Evolution 22 Arachnocampa from Australia. Of these, Arachnocampa tasmaniensis, from Tasmania, is the closest relative. Man and the New Zealand Glowworm 23 Two cther smaller species are known from the Australian (by Mr. D. Williams, Manager of iriaitomo Tourist mainlmd, Arachnocampa flava and Arachnocam~arichardsae.

Caves) This booklet attempts to presert to the Waitomo Caves Glossary 27 visitor a gereral knowledge cf the New Zealand glowworm - including details of habitat, life cycle, snare, Bibliography 29 feeding behaviour and light. Acknowledgements 32

ISBN 0-908683-03-0 First EdLtion 1983 EARLY RECORDS OF THE NEW ZEALAND GLOWWORM

The first record of the New Zealand glowworm was by Rev. A.G. Purchas in 1871. He had collected the female fly and larvae of "one or two1' species of luminous insect from mines on the Thames Goldfields.

In 1886, E. Meyrick ot,served that this luminous larva I "h..... Arachnocarnpa flava appeared to be a predatory beetle larva. He stated that the light came from the back of its neck, and thought it would be carnivorous, feeding on minute insects caught in the slimy network of its 'web1. Meyrick postulated that this beetle larva might use its light to attract its l New 1 food. South Later in 1886, G.V. Hudson refuted the writings of Wales ,.... ,z Meyrick stating that the light came from a large sticky ...;g: . Arachnocam .... knob at its posterior end. Furthermore he thought there >/ richariEe was little doubt that its food consisted of decaying vegetable matter as he had never observed flies or gnats captured in the webs. Hudson also disagreed with Meyrick's assumed function of the light. As the light was not shown regularly, he thought the larva used it to escape from enemies, for "when disturbed they nearly al- ways gleamed very briliiar.tly for a few seconds, suddecly shutting off the light adretreating into the earth". He was also quite confident this larva bore no relation- Distribution of the genus Arachnocampa [after Kermode ) ship to any beetle fmilies, and was in fact a small 'gnat1 or fly.

These early observations of the glowworm are very in- teresting when compared to what is now known about this creature. Meyrick was quite wrong about the positioning of the light and about the larva being from a beetle family. However his observatiors were correct on the feeding behaviour (carnivorous) and function of the light (prey attraction). Hudson, on the other hand, was ac- curate in describing the glowworm as the larva of a %all fly and stating the posterior position of its light. He was incorrect however, on his other statements - the glowworm is not vegetariar, and nor is its light a means -3-

of escape. LIFE CYCLE In 1886, Osten-Sacken from Germany, assigned this insect Like that of most insects, the glowwon life cycle has to the family MYCETOPHILIDAE, but he was unsure about to four stages - egg, larva, pupa and fly - with the entire which genus it belonged. F.A.A. Skuse (sydney) in l890 cycle taking approximately ten to eleven months. In the named it as Bolitophila lucinosa. The Englishman, Glowworm Cave there is an underlying annual cycle with a F.W. Edwards, 1924, noted that some of its characters new generation starting in late winter/spring (August - were unlike those of the European Bolitophila which feed October) each year. However there is considerable over- on the interior of fungi, form no web, and pupate in the lap between each stage of development, with most stages ground. He considered that there were sufficient dis- being present throughout the year. tinctive characters to establish a new genus, Arachno- -cmDa. Sdwards chose this name because of the spider like nabit of the larva forming webs adusing them to catch insects (spiders are scientifically referred to as Jrumer autumn / winter spring kuj -;:-3;:;::ies) . 1 1

Adults (eggs) The preferred habitat of the glowworm must include the following five major factors: 1) A hunid atriosphere to prevent the glowworm from drying Pupae out. 2) A suitable hanging surface, such as the ceiling of a cave, from which the larva can suspend its fishing lines. j) A relatively still (windless) environment to prevent the long sticky threads from targling. 4) h adequate supply of small flying insects for food. 1 ! 3) Darkness, in order that the glowworm's light shows. JFMAMJ JASOND The combination of these factors means that the glowworm Seasonal frequency of stages in the glowworm g as a very specialised environmental requirement. Suit- life- cycle. able places exist in forests, tunnels and of course zaves, habitats in which the glowworm may be found a: throughout New Zealand. The glowworm egg is spherical, 0.75 millimetres in diameter. When first deposited the egg is crem in colour, but will change to either light brown or orange-re6 within a few hours. The eggs are sticky and adhere to the substrate - in caves they are deposited directly onto the walls. The 'incubation' period is 20 to 24 days. weight or size and this de2ends on the availability of Luminescence does not occur in the glowworm egg. At food; an extreme exanple being a glowworm in Ruakuri near hatching the larva splits the skin of the egg and crawls the rockfall which is about 18 months old. The 'annual' out. cycle starts in late winter/spring, so a plentiful supply of food for the larvae during this period may cause early pupation and adult emergence before the following spring.

The larva is the only stage of the life cycle that feeds. The pupa is a transitory stage, and the adult has no mouth. This is why the larval stage is so long relative to the others. The larva has to store enough food re- serve to 'feed' the pupa, the adult, and if a female, the Larva emerging from the egg. (after Richards) eggs of the next generation.

Larva: When newly hatched the larva or worn is very small - three to five millimetres long and 0.33 millimetres a- cross. The larva immed5ately commences the building of a nest and by letting down sticky threads and 'switching on' its light, is able to attract its first meal. It is hy2othesised that cmnibalism is quite inportant for the newly hatched glowworm, as very few insects are small Glowworm larva removed f mm its nest (after Richards enough for the tiny larva to handle. Other young larvae would be one of the few food sources of similar size. PUDa : Before pupation the larva shrinks and becomes opaque. It The larva grows over a period of several months, to reach removes some of its fishing lines leaving an encircling a length of 30 to 40 millimetres. It is not necessarily barrier of shorter condensed lines. This may act as a confined to its nest being able to move 20 to 30 centi- protective shield to the pupa with the clear space pre- metres, and if greatly disturbed may move several metres. venting the fly becoming entanglsd after it merges. The Movement is by waves of muscle contractions passing along larva suspends itself vertically by a long thread, in its body - like the movement of an earthworm. this circle of lines, to pupate. The suspensory cord, The only part of the larva that is hard is the head cap- formed from the larval nest and its supports, enends sule, much like a 'crash helmet'. As the larva grows its from the ceiling to a region of the thorax. 'helmet' becomes too small and has to be replaced by Sexual differentiation first becomes evident in the pupal moulting. During total larval development there are four stage. The female is larger and stouter than the male, moults, with each larva stage being referred to as an and it possesses txo prominent papillae at the end of its 'instar' - first instar (newly hatched) to fifth instar abdomen, which although present in the male, are smaller. (last stage before pupation). Larval development in The female pupae range from 15 to 18 millimetres in total takes eight to nine months, but with considerable length and the males from 12 to 14 millimetres. individual variation. The triggering factor is body Both the male and female pupae are luminescent, thorax and abdomen. Both although the light is in- sexes are also inter- termittant. Luminoscity mittantly luminescent, in the male pupa stops with the female light be- during the last two or ir-g rather larger and three days before emerg- brighter than that of the ence of the adult. In male, again a reproduc- contrast, luminescence in tive factor. The eye of the female becomes more the glowworm fly is very noticeable in the latter well developed taking up stages of its development 90 % of the head. They (a device to attract male are thus very sensitive glowworm flies). to the lights around them. Two or three days before

I emerging, eggs become Below is a table that visible through the shows the size differ- lowworm pupa (ofter Kermde) transparent pupal skin of ences between the male the female. and female . The male is smaller in both bodj usa development takes between I2 ad 13 days. length and wing length. It also compares the bush dult : glowworm with the cave 5e adult fly may emerge from the pupa at any time of the glowworm, showing that Adult fly emerging the ay, comi~ghead first, pulling its wings and legs after adults in the former are pupal case (after Richards ) t. The fly ' escapes' from its pupa case by nuscular some 20 % smaller. ontraction and expansion of the body, and wriggling of he legs. After emergence, which may take up to an hour The adult flies have two purposes to their life. Firstly r nore, the fly hangs head down from the pupal case un- reproduction and the continuation of the species. A il dry, then turns up the other way mtil its wings are second function is dispersal of the species; the adults trong enough for it to fly. being the only stage that can move easily over a significant distance. hs sexes are quite distinct, the female's body being en- srged by eggs which are visible through the body wall, r~dthe male's body much smaller and narrower. Both MALE FEMALE lies are sluggish in flight and move only short dis- Bush Cave Bush Cave ences, one to two metres at a time, with the male being Bodylength 9-1 12-15 10-13 13-16 IIP more active of the two. In flight they make a buzz- ng nolse. When at rest their wings are folded over the Wing length 6- 7 7 - 8-5 7-5-9 9-12

A millimetres When more than one male is waiting for the female to emerge from the pupa, each a-ctempts to f erti- lise her the moment the tip of her abdomen is free. The successful male has to fight off the attempts of the others.

Aft er mating the female lays her eggs. She has a short life span, from less than one day up to three days. On the other hand the male usually lives for up to four days being capable of ferti- lising more than one female. Adult glowworm flles: a) male fly, b) female fly (after Richards ) Male and female flies mating latter Richards 1 Mating : During the latter stage of its development, the female pupa is lminescent, a device to attract a mate. Khen Oviposition: gently rocked, as when a male fly alights on her, she Immediately or sllortly after fertilisation, the female 'lights up' (this action can also be brought about by lays her eggs. When about to lay an egg, she feels for a 'tickling' the two papillae at the end of her body). It- suitable'.spot on the substratum with the tip of her abdo- is not uncommon to see one or more male flies 'sitting' men. She then brings her abdomen under her body followed on the female pupa waiting for the fly to emerge. by violent contractions and flexing movements of her Mating usually tskes place as soon as the female emerges. body. Her abdomen is then brought back to a normal However it may be delayed for several hours if there is position, and the tip gently touches the substratum to no male fly immediately available, in which case the fe- deposit an egg. Each egg is deposited singly. Egg lay- male will continue to glow. With the female light being ing is either continuous or sporadic over a period of larger and brighter, it is possible for the flies to dis- from one to 24 hours until all eggs (on average 130) are tinguish between the sexes while in flight. It is laid. The eggs are found in clumps of 40 to 50, usually thought that tactile (touch) and olfactory (smell) Organs on the fringe of ar. existing colony. The female usually may also be involved in this attraction of the opposite dies immediately aft erwards. sex. TIX NEST AND FISHMG LINES however, move backwards as it has small bristles on its body that 'zatch' on the nest. To overcome this, the The glowworm larva builds a hollow, tubular nest of silk larva folds back on itself and moves in the opposite di- and mucus which it suspends from the cave ceiling by fine rection. When at rest the larva lies on its upper side, silk threads. The silk and mucus is exuded from glands that is on its 'back'. in the larva's mouth. From this nest the larva lets d0.m up to 70 strings of The larva lifts the front part of i~sbody into tbJe air sticky droplets. These are the ' fishing lines' , comiosed to search for a suitable nest site. It will bend forward of a long thread of silk with a series of droplets with a sudden darting movement, and then gently, but de- arranged at regular ~ntervals. These droplets vary in liberately, deposit a drop of silk onto the rock, forming size, but the average is one millimetre in diameter and a fine thread that wlll act as a brace. This process is 1.5 millimetres in length. The length of each individual repeated, with t:ie larva movlng forward into the drop- fishlng line varies also - with extremes from one centi- 15 lets, until mucus a~c silk have passed down the whole metre to 30 centimetres, but usually around centi- length of the body and the nest is cozplete and hollow. metres. These long lines show the great tensile strength The tube or nest appears as the larva moves forward with- of this silk. The fishing lines requlre a lack of air in it, and is left behlnd rather like a s~ail'strail. currents to be effective, otllerwise they would tangle and The xest is approxinately 2.5 times the length of the break. larva, that is about ten cer-tinetres. The nest is very To form rhese fishing lines, muscle contractions cause plastic enabling the larva to move easll~. It cannot the head to move backwards and forwards three times, during whic' mucus can be seen to accumulate around the head. With the last contraction, the head is drawn slightly within the body causing the droplet to appear. The larva rocks its head up and down five times while o3enin~and sk~ttingits jaws, during which the droplet is lowerei on its ~Lread.

Ineat can be built in as short a time as ten minutes. One larva ti;t ?ad its nest destroyed was observed to crawl along the wall to motner spot a short distance a- way. Within 2@ minutes

Glowworm larva in its nest -12- -13- FORMATION OF THE FlSHlNG LINE FEEDING BEHAVIOUR

The larva is the only stage in the life cycle of the glowworm that eats. It uses its light to attract prey (insects) towards the sticky fishing lines, in which they become ensnared. The glowworm is not selective in what it feeds upon, eating anything that gets caught in its lines. In the Waitomo Glowworm Cave the main food is the midge Anatopynia debilis which breeds in the river mud. However other midge species, mosquitoes, caddis-flies, stone-flies and other insects also form part of the diet. In soEe circumstances glowworms have been seen to eat small snails and millipedes that get caught in the nest. Studies of the glowworm anatomy show that the two papillae at the end of its body contain special sense organs that are designed to detect vibrations. They consist of an arraagement like an elastic thread on which are wrap- ped sense cells. With these special organs, the glowworm is able to register the struggles of an insect trapped in its fishing lines. When the larva senses a 'catch', it crawls down the appropriate line until only its posterior half is left in the nest. Waves of contractions travelling along its body allow the larva to haul up the line. This is done by the larva reaching down and holding the line in ,its jaws. A wave of contraction raises the hanging part of its body along with the fishing line. The line is then a Gloworm hangs front third of body down out of nest. held by bristles on its body, while the larva stretches down the next two or three droplets. This process is re- b 1 Three contractive waves pass along front half of body. peated with the complete cycle taking little more than a second. Large larvae can haul up a line at an average c) Mucus accumulates around head of glowworm. rate of two millimetres per secocd. d) Head is slightly withdrawn The animal usually ceases struggling soon after it is and droplet forms . caught in the line although it is not dead. This is be- e 1 Head moves up and down while lieved to be due to acid in the mucus of the lines act- droplet is lowered on a thread. ually paralysing the captured prey. This would be very (after Stringer and Kermode 1 advantageous as the less the insect struggles, the less -q4- CAPTURE OF PREY

a) Prey attracted by light of glowworm. b) Prey becomes entangled in line. Glowworm detects struggling prey's VI bra t ions. cl Glowworm slides partly out of nest and down line. d) Glowworm contracts body to lift line and prey. e) Glowworm arches down next 2 or 3 droplets and repeats the lifting process. (after Stringer and Kermode 1 tangled the lines will become. When the prey is hauled system of the glowworm. up it Is bitten whereupon it dies. The glowworm larva 2) Luciferase - the en- sucks out the juices, and if prey is less plentiful it zyme that acts upon luci- eats the whole insect. When the glowworm is hungry it ferin. An enzyme is a will glow more brightly. biological catalyst that Cannibalism is a fairly common occurrence, with larvae is needed for the reac- eating other glowworm larvae, pupae, and adult flies. tion, but is not itself Larvae have been observed to fight, especially when their altered. nests are too close together, with the victor eating its 3) The energy for the op~onent. When eating a pupa, the preying larva climbs light comes from ATP (Ad- down the suspended rjupa to suck out its juices. Oc- enosine triphcsphate), casionally adult flies are caught in tke larval lines and which is a very important eaten. biological energy source. 4) Also required for this To keep the fishing lines clean end in good repair, the reaction is oxygen, which larva removes the remains of its meals from the web. is the reason there is These remains are contairled in a aroplet which is lowered such an extensive system on a thread ur.til it either breaks or is dropped. Sim- of respiratory tubes. ilarly, the larva cefaecates by lowering the posterior half of its body down a fishing line to rake a large In the reaction, then, 'excretory' droplet (on the line) wnich is also lowered luciferase (the enzpe) mi dropped. acts upon lur.iferin to Anatomy of the glowworm larva forii! an 'electronically (after Kermode 1 excited' product which using tl~e energy from ATP, emits light. The light organ is formed fror. the swollen tips of four excretory tubes (malpnigean tubules). This light organ Luciferin + Lucifeme + ATP + oxypn lies within a layer of respiratory tissue which acts as a reflector, directing the light jownwaras. The respiratory tissue is co~posedof a network of fine tubes 'excited product' + Luciferase (tracheal tubules) wk.ich supply oxygen to the insects in- ternal orgms (the same function as our lungs). The large nmker cf thzse tracheal tubes evident on the light LlGH T organ show that it is profusely supplied with oxygen. This same system of light is used by ell other lumi- The chemical reaction producing tnis light involves nescent organisms. Each organlsm hoxever has its own several components: kind of luclferln and luciferase (they differ slightly in 1) Luciferin - a waste-product formed in the digestive their chemical mike-up), but all give $1,:- :,me him 0.C light production. It is often termed 'natures cold thought to be due to an ability to restrict the oyygen light' as very little of the energy entering the system flow or other chemicals to the light producing organ. is lost as heat (conpare with an electric light bulb which gets very hct). This k.iologiczl prod~ctior. of The glowworm douses its light wher, the light level a- light is pernaps the mcct efficient energx-em] sziori rour:d it is too high, or when it detects severe vibra- systerr! kr~own. tions due to especially loud, prolozged or unusual noises (The gloxworms of Te Anau live in a very noisy cave). The light of the gloxhcrm is a blue-greer colour, at a wavelecgth of 487 nmoaetrts (m)). Glowworms have a two-fold FuI.pose for their light. They use it to attract insect prey, which become ertagled in the sticky lines. The female pupae and adults use their gamma rays U.V. lights to attract the oppcsite sex for mating. In the 0.001 100 i ; 10 000 Wavelength da.rk.zess of tne cave this is a very practical attractant ( nanome tres) systeE. (The lights of the male pupae and adults seem to have LO practical fur.ction arid magi just be relic geretic or larval characteristics.)

0 \ ., ., , 0 visible light '. / \ I- 1- . 1 blue j ' green )sllow orange red 1 There are both biological md phgsical factors cortrol- ling the size of the gio~wormpopulatio~. Thsse biological factors relatf. to other orgaisns or interac.tions ~lowworrn between glowworms. Phj-sical factors are those of the erA- light vironment . Comparison of the glowworm light with other parts of the -Biological Factors light spec1 rum. Predators: I NOTE: 1 nm = IO-~m = 0.000000001 m -- U.V. = ultra violet 1 Inside caves, the gloxworm is fairly safs from predators. However,, there are two species cf harvestman that have been okserved to attack glowworms. Hecdea myersi cavern- icola is a small, orange harvestmar, that is a permZent The glow~cm ca! shSrle it.s ligkt co~:tinucusl:?, but as -- r:oteU by ea1.1~observers iar, extingulsi-l it qulte sudder.1~ cave dweller. It preys on the eggs ad3oung larvae of the glowworm. ilegalopsalis twmis a larger hervestman or more slouij.. It wa: =ar>ier hypcthesis~d thzt the sudden qtiinc,.hing iias due to the gloh~,orm retracting its with very long legs. It differs from Bendea j.n being a light withj11 a sllizid inside its abdomer,. This is r-ow cave visitor, entering onlp in search of food or shelter. Being bigger, Ee~~lopsalisprege on the larvae, pupae and d~sp~ted.Yi,e suadsl; dousillg ueirig sxplsined as tk-e larva rapidly retrra~ir~ginto a 'hide-oat' ir~the sutstrate. adults. Parasites: The slijwir quericnirlg c,f Eite light (in about a ainute) is A common parasite in the Glowworm Cave adother caves is a furigus - Tolpociadium sp. This fungus has beer: cb- been found that the glowworm larva is able to survive served in both larval and pupal stages of the glowworm. long periods (several months) without food. The fungus enters through the skin and the ggt of its Phvsi cal Factors host. A glowworm larva crr pupa infected with fungus takes on a pink colour in the latter stages tefore its Enviroment : death. Once the host dies, the fungus spreads thrcughout One component is flooding. Because of the need to be all the body feeding on the dead tissues. It cm then be close to the food supyly (generally emergent aq~aticin- seen as a white fluffy cylinder ha~gingin the cave (fun- sects) and physical factors (see below) glowworms cften gal cadaver). live in areas prone to flooding. After heavy rain the water in the Glowworm Grotto can rise two uetres in four The rate of fungal Lnfection is very low, as dispersal cf the fungal spores requires air currents which are normal- hours, causing the glowworms to be washed away. Most glowworms are situated high enough in the Grotto roof to ly at a minimum in the cave environment. However, the escape rising waters and on occasions those lower donn te~peratures re~chedin the Glowworm Cave are within the have been observed to survive several hours submergence. optimal range for growth of Tol~ocladium(15 - 25OC) so However, a major flood will reduce population numbers in infection can occur easily. caves considerably. 3espite this there is also a good In 1692, Hudson published a paper, describing a 'wasp' side to f100as. Tneg bring into the cave fresh silt ad that was parasitic on the giowworn. Several pupae were orgmic matter - a suitable hibitat for the insects that collected from the Wellington Botanical Garde~s,"whick make up the glowworns diet. from their shrivelled condition, appeared to have been killed by a parasitic insect". When the adult insects Temperature and Ziutidity: is not a cruclal element in the distribution emerged from these, they were described and named as Temperature They can be found living over the whole Eetyla fulva. There is only this one record of insect of the glowworm. parasitism, but Little work has been done in this area so range of temperatures recorded in the C-lowworm Caves. its significace cannot be gauged A more important physical factor is relative humidity. Interaction 3etween Glowworms: As the glowworm is very prone to desiccation, it requires a very humid atmosphere. In the Grotto, relative humid- Most species of arimai have natural population replating It is thoug5t that the tol- 'devices'. Often this is doze by controlling the spatial ity ranges from 94 to 99 ?;. distribution of individuals to ensure that each has a erance 'range of the glowworm is above 90 %. sufficient food supply. Tn glowworm pollulations it has been observe2 that when individuals get too close one may The importance of the individual effects of the above attick the other - a conflict often resulting in cani- components is hard to gauge due to the difficulty in balism. Thus direct competition between glowworms for assigning reasons for the disappearance of the glowworms. space must also regulate their population. The only factor that can be judged accurately is fungal attack - the white fluffy 'cadaver' (glowworm corpse) Food Su~~ly: left is quite distinct. With other forms of population Food shortage does control population size, but this regulation, we simply have the disappesrance of a glow- tends to be a seasonal phenomenon - during the winter worm egg, larva, pupa or adult. Was it eaten by another there are fewer flying insects. However, it has also glowworm or by a harvestmm? in its web. This species differs in that it spins a flat EVOLUTION web. Thus it seems probable that web building developed first Why such an organism should have evolved is an interest- followed by adaption to a carnivorous diet. A later ing q~estionod which to ponder. The glowworm is well specialization to facilitate trapping of prey was the adapted to its environment, as is shown by the thousands development of a light organ. of glowworms that can be seen in the Gloworm Grotto at Waitomo Caves and other caves in New Zealand. There are two main questions that can be asked about the evolution MAN AND THE Nm ZEALAND GLOWWORM of the glowworm from the ancestral insect.

Did the 'present' glowworm gain its characteristics of The glowworm displays in the caves at Waitomo attract line builcing, bioluminescence and carnivorous behaviour thousands of visitors each year, and as such are an im- gradually, or did they happen suddsnly? Previously this portant economic resource providing both revenue and unique behaviour was considered so strange that some employment. We have seen how the glowworm has very biclogists suggested a 'macro-mutation' occurring. This specialized environmental requirements. How is this would result in the ancestral 'glowworm' gaining all environment affected by man and how is this habitat main- these characteristics at once. Aow that other members of tained? the fauily MYCETOFIiILiilkE are described from around the The two most important factors that can be influenced by world, many of these features have been observed singly man in the glowworm habitat are the climate, (humidity in or in combinatior.. There are species that construct particular) and the food supply of suitable flying in- webs, others that have the carnivorous habit and others sects. Changes to the morphology or shape of the cave that are luminescent. The acquisition of all these can quickly alter the climate inside. In 1975 a solid factors in the glo-morm has resulted in a species superb- air-tight door at the upper entrance to the Glowworm Cave ly adapted to the damp cave environment. was replaced with an iron grille door to improve ventila- The second question is, if these characteristics develop- tion over the busy summer period. In winter, however, ed gradually, then in what order did they appear? Again warm air inside the cave was able to rise to the upper we look to other oenbers of the WiZETOPEILIDAE. Some levels and escape from the cave at an unprecedented rate. species, a few of those living inside fungi, build sticky These greatly increased air movements removed much of the webs but are not carnivorous, i~steadthey use the web to moist&e from both the cave atmosphere and cave walls. trap fungal spores which ar? ingested along with the web. The glowworm habitat began to dry out and numbers dropped In another f~mglzsinhabiting species minute bugs are also with each winter. In early winter 1979 the remaining caught in the web and eaten along with the spores. Many glowworms began turning their lights off ar,d the cave was species actually b:;ild webs either on a single plane or closed to the public as an investigation began. In three in three dimensj.ons and are of carnivorous habits. months the display had returned but the cave was left un- Several of these live in cave habitats. Another species modified while detailed research was done on its climate. has biolnminescenco whi-h appears to be associated with It is likely that the greater movement of air inside the fat cells but an ast~l.allight producing organ is absent. cave increased the distribution of spores of a fungus At least one other species related to the glowworn uses a that kills glowworms and nortality from this agent also l~minescentorgan tc attraot prey which are then trapped contributed to their decline. One of the research recom- runoff and whether anything can and should be done to mendations was to seal off the upper entrance again and restore or enhance their habitat. keep the air tight door closed in winter and left open during summer. This was done early in 1981 and the cave In the past the mantle of rainforest was able to absorb climate immediately stabilized. Since the restoration most of the rain falling on the Waitomo River catchment of the high humidity in the cave the glowworm population and then release the water slowly into the main river has responded with each generation and nmbers are now at channels. With the removal of the forest cover rainwater a level consistent with a stable healthy climate. There moves quickly down the valley slopes often taking topsoil has also been a reduction in the glowworm mortality with it. It is likely that flooding has increased both caused by the fungus. in frequency and peak levels over the last century. The less frequent higher floods tend to scour the bed of the The total population level that the cave can sustain is Grotto while the more frequent smaller floods deposit limited by another c0mponen.c that man can influence - silt and mud. The top ten centimetres of the river bed this is the glowworm food supply. Here it is not changes is rich in oxygen and supports much aquatic life includ- inside the cave but outside, in particular changes to the ing the larvae of insects crucial to the glowworm food Waitomo River catchment upstream of the caves. The supply. Hence the scouring or purging of the riverbed Waitomo that Tane Tinorau* knew was vastly different to adversely affects stream life and glowworms. If there is Waitomo roday, but already the great rainforests were be- a long period between floods the glowworms colonise the ing destroyed, first for millable timber then as grass- lower walls of the Grotto and many are swept away when land farming became established. Along the bottom of the the water does rise. Some movement of the water level is Waitomo Valley the Waitomo River meandered through swampy essential to stream ecology. Storm events release much wetlands rich in bird and insect life. Today almost all organic matter into the streams replenishing essential of the thick forests have gone as have most of the wet- organic nutrients. lands that provided the breeding ground for numerous species of aquatic insects. Nany of these insects in the The question is sometimes asked, "Do large numbers of egg, larve or pupa stages are carried into the caves by tourists passing through the caves have any effect on the rivers an3 as adult flies are attracted to the lights of glowworms?". This is unlikely. The occasional baby cry- glowworms. It is likely there has been a significant de- ing or boat banging sometimes causes the younger glow- cline in the numbers of insects coming into the caves worms to extinguish their lights but it is difficult to over the last 100 years. In 1983 new research was start- imagine any 'people' factors affecting the glowworms on a ed to exmine the ecology of these insects. The objec- long term basis. Carbon dioxide is breathed out by tives of this research are to establish which species are people and in some deadend passages this can have detri- importalt in the glok,worm's diet, how far upstream they mental effects on the cave formations. Experiments have originate, how much their habitat has been altered, if shown that glowworms have a higher tolerance to carbon they are at risk with oil, insecticide, or fertiliser dioxide than humans so they will be affected by carbon dioxide long before the glowworms. Measurements have shown that the CO2 in the Grotto is sometimes slightly * Tale Tinorau was a PIaori Chizf wllo in the company of higher than normal but nowhere near levels dangerous to Fred Kace, an English Surveyor, first explored the Glow- people. worm Cave in 1887. For some years now a record has been kept of habitat -27-

factors in the Glowworm Cave. At several sites in the GLOSSARY cave weekly records are taken of maximum and minimum air temperatures, rock and water temperatures and evapora- Abdomen - The tail part of an insect. tion. Variations in air temperature and humidity are Anatomy - The study of the structure of the body. constantly recorded onto charts by thermohygrographs. Outside the cave, climate readings are taken weekly and bioluminescence - The biological production of light. the river level is continuously monitored at a station Cannibal - An animal that eats its own kind. near Aranui Cave. Carnivore - AIL animal that feeds on flesh. Inside the Glowworm Cave two sample colonies of glowworms Desiccation - The complete loss of moisture. are counted each week. Within this population the occurrence of larvae, pupae, and adult flies are noted, as is Larva - The 'grub' stage in the life cycle of an insect. the incidence of fungal attack. The number and size of (plural - larvae) insects caught in tne lines of a small glowworm colony Macro-mutation - A very large genetic change (mutation). are also recorded. Oviposition - The process of egg laying in the insect. Recent research on glowworm ecology and the hydrology of Papillae - Small extensions of the insect body, usually the Waitomo catchment has given us a better understanding containing sense cells. of how man influences the ecological and physical environment of the glowworms in the caves at Waitomo. Many Farasite - An organism that lives in or on another, with of the research recommendations have already been imple- detrimental effects to the host. mented with positive results and from this understanding Predator - An animal that hunts and kills other animals of the resource it is likely that the glowworms will be for food. attracting visitors for many years to come. Pupa - The 'cocoon' stage in the life cycle of an insect. (plural - pupae) Pupation - The process whereby the larva changes its body functions and shape to become the adult insect. The organism in this state is known as the pupa. Spatial Distribution - The distribution of organisms or objects in a defined area. Substrate/Substratum - The underlying surf ace. Taxonomy - The scientific naming of organisms. The full taxonomy of the Sew Lealand glowworm is as follows: Phylm: krthropoda - animals with external jointed skeletons. Class: Insecta - animals with six legs and three main parts to the body. Sub-Class: Fterygota - winged insect. -29-

Glossary contd. BIBLIOGRAPHY

Order: Diptera - two winged insect (as opposed to four wings). Bircham, D.N. 1975 Waitomo Tourist Caves A.H. & A.W. Family: MYCETOPHILIDAE - fungus gnats. Reed Ltd., Wellington. Genus: Arachnocampa - larva building a web. Species: Arachnocampa luminosa - N.Z. glowworm. Edwards, F.W. 1924 A Note on the 'New Zealand Glow- Tensile Strength - Strength of stretching. worm' (Diptera, Hy~eto~hilidae), h.Map. Nat. Hist. v. 9(14), Thermohygrograph - An instrument that continuously measures humidity and temperature of the air, auto- PP 559-74. matically recording this information on60 charts. Ganguly, G. l960 Notes on the History and Anatomy Thorax - The middle section of an insect - has legs and of the Larva of Bolitophila lumi- wings 'attached' to it. --nosa of New Zealand, J. R. Nicrosc. Soc. v. 7O(2), pp 137-yC.

Gatenby, J-Bronte & Ganguly, G. 1958 On a Possbile Explanation of the Sudden Dousing of the Light of the New Zealand Glowworm (~rachnoc-a luminosa), J,R. Nicrosc. Scc. v. 76, pp 146-48-

Gatenby, J.Bronte 1959 Notes on the New Zealand Glowworm Bolitophi_la (~rach~ocama)lumi- -, Trans. R. Soc. N.Z. v. 87(3 % 4), pp 291-314.

Gatenby, J-Bronte l960 The New Zealand Glowworm, Tuatara V. 8, pp 86-92

Goldschmidt, R.B. 1948 Glowworms and Evolution, Rev. Sci. Paris v. 36(3293), pp 607-12.

Hddnon, G.V. 1886 A l,~mi.n~usInsect Larva in Nev Zealand, Entonol. Hon. Nag. v. 27, pp 99-1C1. Bibliographjr contd.

9udson, G.V. 1892 Note 051 an a~t-likeInsect (Betyla iulva Carneron) parasitic in tke PTew Zeal and Glowworm, Trans. N.Z. I-1st. v. 25, p 164.

1890 Description oT a Luminous Dip- Jackson, J.F. 7974 Goldschmidt ' s Dile~rnart:solved: Skuse, F.A.h. terolls Insect fro? ;Jew Zezlad Fiotes or! the larval behaviour of a (f;a!.~~;~to~hiii.5se), Prc,:. Lim:. new neotrol;j.cal web-spiiinirlg SOC. 1; .S.W. &a series, v. 5, Mycetop1:ilid (~i~tera),An. Fi31. pp 677-79- Nat. v. 92(,?), pp 24-0-115.

1983 kraitomc: G] ornorm Cave, Aranui Eermde, L. 0. 1974 The New Zealand Glowwor-m Arachno- Srnjth, R. ?.v€. Run:q~ri :aye =LC Sur::3uridin; campa luniinosa, N.Z. Speleo. Eui. Dist~:ct; A.H. & X.W. Reed Ltd., v. 5(91), pp :13-320. W~llington.

Keyrick, E. $280 A Lunicous Insect Larva ill New 1$1i;7 The Larlral Behaviour of the ?T:'TFw Gealmd Rntomol. Pion. Nag. v. 22, Strlllger, 1.i.N. Ze.-la;ld GLowworr~Brackliocal2~,a pp 265-7. :ur?liricsa, m V. 13, ?p 107-17. Osten-Sacken, C.B. l686 A Lu'nous I~sectL,arva In New Z&1, P.A. 1971 ?iztures Night Lights, National Zealsd, E~itonol.Mon. Ilrig. 17. 23, pF $33-34. Geoa~ap?.ic Ally, v. l40(1), gip "445.

FxgsLey, ;.W. ,1980 Ecolop,~of she Beb: Flealand G1zni-worrn Arac-kccanpa 1rmin.osa {Slrusej (Di~t,era: Mycztophilidae) in Tcijrist Caves et Waitor~izUnpub- lished Thesis, Urliversity of tucklend.

Furckas, A.G. lP7'1 Exhibit of two Sp?cies sf Lamp- I would like to take this opportunity to thank all those pe9pl.3 who helpel me in the compi1a';io~ of tlil..s bo~klet. Firstly to Peser Di~~~onl,cl~airmar- of th2 Waitorno Caves Xuseum Soc. Inc. , for j.nt~.oduci.ng the idea. Tha~ikcmu.st go A;o the other insm3ers of the K~~seumStaff, expecially T:-evor lrr'ortliy, Diana Zarey, Yalcolrn Wood, Martha Ash m6 Robert Arrell, for their cements an& alterations to the szript. Also tc Dave Willia~swho made comments 01 tk-e mair! script, ad..,.rots the last section on "Man a~dthe Xsw Zealand Glow~orm". hT1.itingthis bocklet has been h unique experience for me, one that 1 really enjoyed. Thank you. Tlie Fuscum, opened on the 17th October 1381, is operetod by the Wsitonr, Caves Mlsexm Societj.,

Inc. It is 8 non-profir making

orgnnisation, f orned l11 1973, to cleplct; th? cultural arid natural history of WaiJ;ono Zavec.