Curious crane flies

1 ARE THESE LONG-LIMBED INSECTS ACTUALLY FLIES?

Yes, these are true flies in the order Diptera. The name translates as ‘two wings’, and reflects the fact that flies have two wings, unlike the four in other flying insects. Look closely at a crane fly, and you should see a little pair of stubby ‘drumsticks’ sticking out of the thorax. These are halteres, thought to have evolved from what was once a rear pair of wings. They vibrate in flight, acting as stabilisers, like the gyroscopes in drones and helicopters.

2 HOW COME THEY CROWD INSIDE OUR HOUSES?

Commonly known as ‘daddy-longlegs’ in the UK, crane fly adults ( right) bump clumsily around our homes after being attracted to lit windows at night. Their sudden appearance, usually in autumn, is due to a mass hatch of maggots. Called leatherjackets, the larvae ( left) have passed their time munching roots in damp soil, and look fairly ordinary save for, as Erica McAlister puts it in

The Secret Life of Flies, “their most exquisite anal breathing tubules”. Sadly, due to pesticides, huge swarms of crane flies are mostly a thing of the past.

3 WHY DO THEIR LEGS TEND TO FALL OFF?

Their delicate, gangly limbs seem too fragile to be much use – almost a liability. In fact, fragility is a secret weapon. As McAlister’s book explains, a bird that attacks a crane fly will often end up with a leggy mouthful, enabling the insect to escape (albeit with fewer limbs, as they don’t grow back). Their legs are also an adaptation for perching on blades of grass.

Ben Hoare