Ruud Kleinpaste: Tossing some soil for the antlions

Saturday Morning with Jack Tame

A moth or so ago I was walking around the Halswell Quarry, looking for native bees. We have about 28 species of these bees in New Zealand, and the unfortunate thing is that we know very little about these creatures.

A new book by Rachel Weston described how these tiny bees make holes in the ground where their larvae (babies) are raised. The air space around those tunnels is quite busy, with bees coming and going constantly; some air traffic control could well be a useful asset to these tiny habitats!

I didn’t just find a heap of native bees but also a few holes of significant size: conically shaped holes with a diameter of at least 30 millimetres, situated in a dry bit of soil, protected from regular rain fall.

It reminded me of the holes I used to have under the eaves of our old open car port.

In the pit of these holes live a very clever Neuropteran insects, known as Antlions. The cool thing is that this extraordinary species is the only “antlion” endemic to New Zealand – it’s ours and it lives nowhere else in the world.

The fully-grown adult is a sizeable lacewing with beautiful wings, shaped by a multitude of fine veins. It’s not a strong flyer, but elegant when it climbs up the vegetation around the area where it grew up. This insect feeds on pollen and small insects, but it is not very long-lived.

The larvae (young versions) of these antlions are the ones that create those magnificent holes in the soil through clever movement of their bodies. Excavation is a fine art.

They are predators, meat eaters, and the holes are their traps. These predators are equipped with a mean set of jaws.

When an insect ventures into the realm of these antlion babies, they will tumble down the steepish slope, down to the bottom in the centre. That’s where the antlion larva is waiting to grab its prey with impressive, sharp mouthparts that look like pincers.

Their diet is any invertebrate that is small enough to be subdued: crawling caterpillars, small beetles, native bees, ants that made navigation errors, etc.

The coolest part of the antlion’s arsenal is the tactic of making the potential prey lose their footing!

As soon as an ant tumbles down the slope and dislodges some sand or bits of soil, the antlion baby starts tossing some soil, throwing sand uphill in the direction of the prey to make it lose its balance!

And of course I can’t help fuelling the fight by dropping some soil particles into the antlion’s clever trap – now this is a fight to watch!

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