Springtails

Springtails are tiny but really, really cute. They are just visible to the naked eye but a stereo-microscope will reveal them in their minute perfection. They come in several different shapes – elongate or almost spherical. They are “primitive” wingless insects, with antennae on their heads, 3 pairs of tiny legs and a springing organ on their underside. This acts as a defensive organ allowing springtails to evade predators and flicks them quite large distances – 10 cm for an animal only 1-3 mm long! They have softer bodies than other insects and this makes them vulnerable to desiccation. They react to dry conditions by going into a state of suspended animation or survive as drought-resistant eggs.

We say springtails are “ubiquitous” – wherever there is soil, there are springtails. They live in warm, moist soils in tropical rainforests, they have a brief flurry of activity in summer in the cold soils of Antarctica and they live in all soils in between these two extremes. They live in agricultural and garden soils or in newly formed soils on glacial moraines at high altitude. They live in the sand of intertidal zones of beaches where their water-repellent skin helps them wrap an air bubble around themselves to wait until the next low tide when they can move about in the drained air-spaces between sand grains. Wherever you find springtails (and that is everywhere!) you will also find soil mites. Together they are lumped into a group of small soil animals called “microarthropods”.

Springtails live in air-filled pores mainly in the top 10 cm soil, in the leaf litter layer, in dung pats, compost heaps and any rotting animal and plant matter. Though they are tiny, they can occur in very high numbers – I once collected the equivalent of 1.5 million per square metre under a dead bird, but usually they are around 25,000 per square metre in grassland soil. Some live in vegetation, in leaf litter and dung or only in the deeper soil depths but they can move up and down the soil/litter/dung/vegetation profile depending on weather. In the soil, they use the soil pores to move through as they are too weak to make their own tunnels through soil.

Springtails are “goodies” and feed mainly on decomposing organic materials, helping break it down. But they do love fungi. Inspect the next mushroom you pick in the field before eating it. Chances are you will see small purple spots moving over it, and between the gills of the mushroom. They are pretty impossible to wash out – they just add a little animal protein to your meal! Some are pests of legumes such as the lucerne flea.

Springtails clog the works! Heavy rain flushes springtails out of their air-filled pockets in the soil and they collect on the surface of puddles. Springtails have a water-repellent skin and when they land on water, they float. You will often see a purple scum on puddles – this is a raft of live springtails trapped on the water surface. I have seen so many on the surface of a swimming pool that they clogged the pool filter.