What’s bugging you?

Pamushana | December 2019

After that first sprinkling of rain and the trees drawing on their energy banks to produce the first green leaves, we’ve seen a rainbow array of arthropods appear. Arachnids and insects are all going about their business and are of enormous importance to the functioning of a natural ecosystem.

I was delighted to discover one of my favourites, the red velvet mite, scurrying about in his bid to woo a female. Males arrange their sperm in a “love garden” in an organized area of twigs and grass. When it is arranged they attempt to lure females using a silk trail that outlines a path to their garden. They may even perform some “dance” moves to entice her.

Green lynx spiders (Peucetia) are green but can change to yellowish-green to match faded vegetation or even pinkish-red infusions on green to blend with the environment.

Ants belong to the family Formicidae and are noted for their conspicuous demarcation between head and thorax, segmented waist and antennae elbowed at the first joint. The waist of this ant is so tiny its almost indistinguishable!

These dragonflies were caught in the act of trying to mate, an act which requires complex contortions in flight to be successful.

This citrus swallowtail butterfly was feasting on the nectar of these dainty white flowers. In suburban gardens or farms you can see them around your citrus trees which is where they lay their eggs. Despite their common names swallowtails are often tailless.

This bush looked like a Christmas tree adorned with the brightest baubles you could imagine! Rainbow shield bug (Calidea dregii) are brilliantly coloured, exhibiting a wide range of iridescent metallic hues. Their iridescence is a result of structural coloration. Instead of pigments, the colours are caused by the interference, diffraction, or scattering of light by numerous tiny structures. All the bugs in these photos are rainbow shield bugs – the little round one is an instar which is a stage it goes through between moults in its development.

You have never in your life heard such a loud piercing racket as when you find yourself in a thicket of cicadas! It is absolutely deafening and it physically made my eyes water and my head spin – I actually felt a bit debilitated and had to zoom away from the area after quickly taking these photos. No bird or other predator in its right mind would go anywhere near a mating ground like this, and that is indeed part of the reason for the cacophony.

The high-pitched “song” is a mating call megaphoned out by males. Cicadas are the only insects capable of producing such a unique and loud sound. Some larger species can produce a call in excess of 120 decibels at close range. This is approaching the pain threshold of the human ear! The organs that produce sound are called tymbals, which are a pair of ribbed membranes at the base of the abdomen. The tymbals are contracted inwards causing them to buckle, producing a distinct sound. When these muscles relax, the tymbals pop back to their original position. It’s a similar concept to pressing down the lid of a tin.

Even cicadas must protect themselves from the volume of their own singing. Both male and female cicadas have a pair of large, mirror-like membranes called the tympana, which function as ears. The tympana are connected to an auditory organ by a short tendon. When a male sings, the tendon retracts, creasing the tympana so that it won’t be damaged by the sound!