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www.thevillagenews.co.za
24 December 2019
MY ENVIRONMENT #AllOverOverberg we’ve got you covered. The small, picturesque village of Botrivier lies in the foothills of the Houw Hoek Mountains, en route to Hermanus. The Bot River, after which the hamlet is named, meanders its way through a fertile valley surrounded by mountains covered in fynbos, historical wine farms and fields of wheat. A whole generation of South Africans was introduced to the town of Botrivier as the setting for their favourite TV series - ‘Nommer Asseblief’ (number please). Go online to learn more about Botrivier. Honingklip – the land of beer and honey thevillagenews.co.za/honingklipthe-land-of-beer-and-honey/ At Honingklip Brewery on the R43, ‘brewer and quaffer’, Mark ter Morshuizen and his ‘alewife’, Analize have been successfully combining a love of nature with a love of Belgian-styled beer for the past six years. Beaumont Family Wines poised for a new chapter thevillagenews.co.za/beaumontfamily-wines-poised-for-a-newchapter/ This family-owned and -managed farm situated in the heart of the town of Bot River is home to the region’s oldest wine cellar, originally established in the 1700s by the Dutch East India Company. Named Compagnes Drift, the outpost was a self-sustaining farm that supplied the garrison of soldiers and travellers to the interior with fresh produce. Barrels and Beards wine makers raise over R110 000 thevillagenews.co.za/barrels-andbeards-winemakers-raise-over-r110000-for-local-bot-river-educationprojects/ A rain-drenched day turned into a magical evening for this annual event as the clouds parted and the heavens opened up, a symbolic blessing for the night’s activities. www.pressreader.com www.issuu.com/dwaal
083 700 3319 theagency@thevillagenews.co.za
The Christmas Bug – nature’s magnificent flying machine By Dr Anina Lee
M
y childhood memories of Christmas holidays on the Cape south coast always recall the happy sound of the Cape Turtle Dove and the shrill song of cicadas in the midday heat. In the southern hemisphere, where Christmas falls at the height of summer, cicadas are known to us as Christmas Beetles or Sonbesies. They are indeed besies or bugs (Hemiptera family) and not beetles. So they should rightly be called ‘Christmas Bugs’. Cicadas are found on every continent in the world, except for Antarctica, because cicadas don’t like the cold. There are about 150 species of cicada in South Africa. When I started writing this article it occurred to me that I had not heard cicadas for some years. When I mentioned this fact to my son he was astounded. “What do you mean you haven’t heard them? They are splitting my ears right now.” I had not realised that my ageing ears could no longer hear their screech in the 0.5 to 25 kilohertz range. The song of the cicada Only male cicadas sing, and only those belonging to the group of cicadomorpha can produce sounds that are audible to humans. Cicada sounds have been recorded up to 120 decibels, which is close to the level of jet planes and can damage human hearing. Unlike similar insects, such as crickets, the male cicada does not use stridulation (the rubbing together of body parts) to make their loud sound. Instead, they use a pair of tymbals, special structures on each side of the abdomen, just behind the last pair of legs and covered by a membrane
ABOVE: An adult cicada. RIGHT: A Floury Baker (Abricta curvicosta) cicada. PHOTO: commons.wikimedia.org called a tympanum. The tymbals are ribbed membranes, each having strong muscles attached to it. Contracting and relaxing these internal tymbal muscles causes the tymbals to rapidly vibrate and produce pulses of sound. In some cicada species, a pulse is produced as each rib buckles. The sound so produced is further amplified by the almost hollow abdomen which serves as a resonance chamber. As mentioned before, only male cicadas sing and each species has its own song. They do it, of course, to attract a female of the right species – who responds to the song by flicking her wings. They have an interesting life cycle Cicadas are insects and the breeding cycle begins when adults mate after the males lure the females with their attractive cicada songs. After mating, the female lands in a tree, and she uses her egg-laying organ (ovipositor) like a saw to cut a slit into the bark where she lays her eggs. When the eggs hatch, the nymphs drop to the ground and they burrow down to depths of 2.5 metres into the soil. They then excavate chambers close to plant roots. There they feed on the juices from the tree roots by inserting their sucking mouthparts into the roots. They may spend up to 17
years and go through several ‘instars’ (developmental stages). Cicadas have the amazing ability to synchronise their development so that they all reach the final instar stage at the same time. This is when they all tunnel to the surface at once, leading to a ‘plague’ of many thousands of cicadas. The instars crawl up plants where they shed their skins for the final time, morphing into adulthood. The 17-year cycle occurs most notably in the USA. In 1987, when visiting the north-east USA, we saw branches breaking off trees under the weight of the huge numbers of cicadas that emerged that year. This is the stage when the singing starts. The males die after mating and the females die after laying their eggs. So they don’t have much of a life other than the troglodytic one of the nymphs. What are the biological advantages of a long instar phase and synchronicity? There are some theories that explain advantages to the cicadas of ‘outsmarting’ their predators. Potential predators cannot rely on this food source year after year. One year they are there, and then they may be gone for anything up to 17 years.
An unreliable food source means that the predator numbers remain low. Because the cicadas all emerge in their thousands at the same time, it means that predators are ‘overwhelmed’ by the numbers as they can only eat so many at one time. Other defence mechanisms Cicadas have excellent camouflage. They look like bark, with disruptive patterns on their bodies that allow them to blend in with tree bark. This is why you will hear many cicadas singing, but it’s almost impossible to spot them. They have a capacity to ‘throw’ their sound, which further confuses us. Cicadas are excellent ventriloquists – they are never where you expect them to be. Cicada wings do not reflect light, thereby preventing the typical insect cuticle shine. They are also very strong fliers and are able to fly at high speeds to escape their predators. These facts about cicadas illustrate the evolutionary truth that any species exists only to continue to exist. Cicadas have evolved a complex life cycle which optimises the survival of every generation. Wishing you many happy Christmas Bugs.
