insects

Skate, jump and slide: These bugs are nature’s own water skiers

Wildlife

Water striders are the most conspicuous element of the semi-aquatic bug fauna of Australia. Belonging to the family Gerridae, they are adapted to their life on the water surface due to their distinctly elongate mesothorax and long and slender middle and hind legs. This allows them to “skate” or “jump and slide” in a very characteristic way on the water surface and is aided by the hydrofuge or water shedding properties of the legs. One often first notices them because of a disturbance on the water surface or notices the “dimples” in the water surface created by the legs, or the shadow of those dimples on the bottom of the water body. Tenagogerris euphrosyne is a species common along the east coast from Cape York in Queensland to western Victoria, with this picture taken at a fresh water pool in Sydney Bushland. Here the male is riding on the female’s back in what is known as “mate guarding”: after mating the male remains with the female so that no other males can mate with her. It is a characteristic water strider behaviour and still allows them to move freely on the water surface. Depending on the time of the year, populations can consist of both winged and wingless adults as well as nymphs, with adult size of this species ranging from 7 to 10 mm body length. The winged forms are quite capable of flight and allow the species to locate another body of water if their present one dries up. Water striders are opportunistic predators and scavengers, preying on anything that falls to the water surface. The strong proboscis as seen in the picture allows them to pierce their prey and suck out the juices. Words by Tom Weir, Honorary Fellow, Australian National Insect Collection, CSIRO, Canberra For more images and information, visit http://photography.irwig.com/ and follow the ‘strider’ link.

In pictures: millions of ladybirds swarm radio tower in SA

Wildlife

There have always been an unusual number of ladybirds in Mount Burr, South Australia according to photographer Steve Chapple, but nothing like the sight he stumbled upon recently. Ladybirds are currently swarming a local radio tower in the millions, confounding experts and stunning onlookers who are now flocking to see the phenomenon. They’re four inches deep and the base of the tower is about five metres by five metres, so you’d have to talk in the millions,” Steve told the ABC. So what are they doing? Research entomologist Adam Slipinski, a renowned expert in ladybirds, told Australian Geographic that it’s common for ladybirds to migrate towards prominent landscape features and disperse after a period of time. They do not feed and one of the potential factors of their quiescent period is probably sudden food shortage but changes in humidity, day length and other environmental factors have been listed as potential stimulants. In the northern hemisphere they often form winter aggregations, and these happen here as well, but I think these occurring right now are of different nature and beetles will disperse into more cryptic niches before winter snaps. See the images below.