• Those little black beetles

About every 11 to 12 years a small ground beetle with an unpronounceable name, Gnathaphanus philippensis (right), occurs in huge numbers in our area. The beetles are normally found in leaf litter or under bark where they and their larvae feed on other small insects.

They also have a preference for grain and that’s how they get around. They are attracted to lights on grain ships and hitchhike to other lands. For some reason they undergo a population explosion, oddly about every 11 to 12 years. At this time, they are a nuisance because they are attracted to lights in storefronts, around homes and under street lights. When disturbed the beetles emit a ‘puff ’ of a repellent substance that helps prevent birds and lizards from attacking them. After a few weeks the beetles disappear and are not seen in such numbers for another decade or so. Oddly, shortly after the last outbreak Cyclone Yasi appeared! Ground beetles are not the only insects in our area that have population explosions. Everyone knows about Australian grasshopper plagues that occur from time to time as a response to certain ecological conditions. But other insects also undergo population outbreaks. A small Meadow katydid, Conocephalus upoluensis, is a good example. This katydid occurs Australia-wide. It lives in grasses and can be found in modest numbers most of the time. But occasionally its populations build up causing concern to residents who have “never seen it before”. The katydids accumulate around lights and on shopfront windows.

Several years ago, a Pygmy Grasshopper, family Tetrigidae, turned up in huge numbers in our region. The airport was concerned that their small size and large numbers could clog jet engines and they wanted to know how to control them. The grasshoppers seemed most active at night and were attracted to the airport lights. A simple solution would have been to convert the lights lining the walkways to yellow bulbs. This colour does not attract most nocturnal insects. But the simplest solution was to just wait a few weeks and they would just go away. That is exactly what happened. They haven’t been seen since in such numbers. The numbers of these little grasshoppers (which do not eat grass but are semi-aquatic and feed on algae and diatoms) was incredible. Not only were they abundant at the airport but they occurred in large numbers as far away as Atherton where they could be seen by day on walls and windows. A small earwig, Elaunon bipartitus, builds its populations from time to time and accumulate around and in buildings. Everyone in Cairns knows this insect. The earwigs can be superabundant and are easily transported as they hide in packing materials and in boxes. They are not harmful but their numbers make them a pest. They seem to be omnivorous. After a short time, they just disappear to return a few years later.

Pygmy Grasshopper