Ever seen a toadstool fly?

The answer probably depends on whether you ate it or not.

Along our ridgetop after the recent rains a group of Giant Boletes (Phlebopus marginatus) (pictured left) has appeared. This mushroom is Australia’s largest terrestrial fungus. Some specimens have weighed in at over 20 kg.

Where there are Giant Boletes you will find Toadstool (or Fungus) Flies (Tapeigaster sp.) If you look carefully at the photo will find a toadstool fly diligently guarding its domain (from me!). In the brief time I have spent observing these insects the mushroom surface alternates between a boxing-ring and a boudoir. Male flies patrol their particular mushroom and if another male lands, both rear up on the two pairs of rear legs and appear to box each other with their front legs until one is forced to fly off. If a female lands the process of courting and procreation begins. The resulting larvae feed on the fungus. As they feed, they reduce the large mushroom to a large oozing mess soon afterwards.

Back off! It’s my mushroom.

These flies have been seen patrolling the parasols of several species of mushrooms out at the moment. To see a toadstool fly you don’t need to eat it, just sit patiently nearby and watch.