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16 October 2019
www.thevillagenews.co.za
And there was light
The magic of fireflies Writer Dr Anina Lee
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The South African National Space Agency (SANSA) in Hermanus celebrated the 15th anniversary of its Science Centre on Monday 7 October with the unveiling of several new space-themed Science Centre exhibits. It is a privilege to have such an internationally-recognised organisation in the Overstrand and The Village NEWS regularly covers SANSA’s activities. Go online to read these articles: SANSA Science Centre unveils new exhibits at 15-year celebration thevillagenews.co.za/sansa-science-centre-unveils-new-exhibits-at-15year-celebration/
First opened in October 2004, the Science Centre has welcomed more than 70 000 learners and over 1 000 science educators to learn more about space and South Africa’s space-based activities. Today, the Science Centre boasts several brand-new exhibits, including a replica of South Africa’s second satellite, SumbandilaSAT, an earth observation satellite which was used for monitoring disasters such as floods, oil spills and fires within Southern Africa. SANSA selected as regional space weather centre for the aviation sector thevillagenews.co.za/sansa-selected-as-regional-space-weather-centre-for-the-aviation-sector/
The South African National Space Agency (SANSA) in Hermanus has been selected by the International Civil Aviation Organisation (ICAO) as one of two regional centres to provide space weather services, including solar storm forecasts and warnings, to the global aviation sector. Space 4.0 made easy by Jan Wörner, European Space Agency thevillagenews.co.za/space-4-0-made-easy-by-jan-worner-europeanspace-agency/
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s most people in Hermanus will know by now, October is firefly time. That’s when the magic happens – or rather, the brief, threeweek mating season when flashes of light can be seen in undisturbed habitats like the fynbos. These are fireflies out on the town. Let’s start with a brief description of the fireflies of the Western Cape. We have one species, Luciola capensis – just one of about 30 southern African species and 2 000 species of fireflies world-wide. Fireflies are neither flies, nor on fire. They are actually beetles (Coleoptera), belonging to the family Lampyridae. Some firefly species are quite large – up to 2.5 cm. Our local L. capensis is tiny – about the size of a grain of rice. Metamorphosis As is the case with all insects, fireflies go through metamorphosis. Eggs are laid in spring and hatch into larvae that live in damp soil or leaf litter over the summer and most of the winter. At the end of winter the larval form pupates. The most amazing change occurs during pupation. The cells that made up the larva dissolve into a soup and then reassemble gradually to turn into an adult insect. After about three weeks, the adult fireflies emerge. Adults mate and lay more eggs and the cycle goes on. Metamorphosis is very advantageous to insects as the two distinct forms of larva and adult have quite different functional lifestyles. A firefly larva is a voracious predator of all things slimy in the leaf litter such as worms, slugs and snails. The larva has a vicious bite, injects digestive enzymes into its prey and slurps up the liquefied “smoothie”. This allows it to predate on prey much
2 larger than itself. While firefly larvae live to eat, thus building up stored energy resources for their adult lives, the adults generally don’t bother to eat, but live only to fly around to find a mate to procreate. Matchmaking by night Flying around in daylight has its drawbacks for an insect. For a start, there are more predators around, so many species of fireflies have taken to matchmaking by night. The problem is that it’s rather more difficult to find a mate in the dark, so these nocturnal fireflies have evolved a solution to that dilemma – they make their own light through a process called bioluminescence. Bioluminescence is a “cold” light produced in a special light organ in the terminal segments of the insect’s abdomen. Both males and females use light. Sometimes even the larvae will emit a steady light to warn predators that they are toxic and not good to eat, leading to the misnomer ‘glow-worms’. Bioluminescence is produced by a chemical reaction between a molecule called luciferin, oxygen and an energy source called ATP. This reaction is catalysed by an enzyme called luciferase. Basically the end result of this reaction is the production of a photon of light. Most fireflies don’t emit a steady light, but can turn the light on and off to produce a flash pattern that is unique for each species. The mechanism for flashing is controlled by the same substance (nitric oxide) that is produced by Viagra.
reasons, but the main reason is to find a mate. Females sit low down in the vegetation or on the ground and wait for a male to fly by. If she likes his flashing, she will return the flash as a ‘come-hither’ signal. After mating, the female will lay her eggs in damp soil or leaf litter and then both adults die – destiny fulfilled. Firefly society has its femmes fatales. The female of one species of firefly can imitate the flash pattern of the females of another species. When the targeted male approaches, hoping to make a liaison, she eats him. Such is life – or rather, death. Shine your light on me If you want to encourage firefly magic in your garden, here are a few things to remember: • Switch off all external lights. Light pollution and loss of habitat are the two main reasons why we don’t see many fireflies. Artificial light confuses them. • Do not use snail bait, insecticides or chemicals in the garden. • If your dog is on a systemic tick/ flea product like Bravecto, be extra careful. The active ingredient that kills ticks and fleas on your dog is excreted unchanged in the dog’s poo. Burying it in the garden or leaving it around will kill the desirable soil insects in your garden – including dung beetles and fireflies. Rather pick up the poo and flush it down the toilet. • Leave your soil undisturbed since the larvae spend most of the year in the soil and tilling it will kill them. Rather just add more mulch. If you want wildlife in the garden, leave it to nature.
Fireflies light up for a variety of 4
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Fascinated by space but not sure you understand what a black hole is or what people mean when they refer to the “dark side of the moon”? Well then, take an hour out of your day and watch this video. Learn about Space 4.0 in a way that you will easily understand. Jan Wörner, Director General of the European Space Agency, is an amazing speaker who sprinkles his talk with humour.
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1 - A synchronous firefly. PHOTO: firefly.org. 2 - Lampyrid firefly larva eating a snail. PHOTO: Paul, Flickr. 3 Fireflies enjoy the open air as the sun goes down. 4 - L.capensis firefly. PHOTO: Terry Priest.
