Craneflies are also called Daddy Longlegs because of their long dangly legs
Nature on our doorsteps: Craneflies and leatherjackets
Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into the natural heritage around us and the beautiful biodiversity of the plants and creatures.
The long-legged, dangly Cranefly appears in high numbers generally from the first week of September. Its long, stick-like body, narrow wings, and very long legs make it look quite awkward when it flies.
Craneflies are harmless. They do not sting or bite, and in fact the adult form does not have mouthparts suitable for feeding.
Most of this insect’s life is spent in the juvenile form, as a larva or maggot-like grub that lives underground.
Most larvae only grow to approximately 3 or 4cm long, and they have chewing mouthparts which they use very efficiently to feed on the roots of grasses and decaying organic matter in the soil.
They are generally a grey, brown, or a creamy-white colour.
The skin of the larva is also very tough, which is why they are often called leatherjackets.
The pupa of the Cranefly larva wriggles to the surface and splits open
This toughness is not a deterrent to Blackbirds, however, who are often seen prodding and probing the short grass on lawns and roadside verges with their sharp beaks as they hunt for leatherjackets.
When mature, the leatherjacket larvae bury into soil or moss and form a tough pupal case in which they will develop over the next few months.
When the new adult is ready to emerge, the pupal case can sometimes be seen wriggling to the surface. It splits open along one end, releasing the new adult Cranefly.
These new adults then search for a mate, and the females will lay many new eggs on wet soils, mosses, and in damp grasslands to start the Cranefly life cycle all over again.
The adults are perhaps noticed mostly at dusk, when they drift into houses through open windows and doors. They are attracted by the lights, and so they usually end up dancing around lighted ceilings and lampshades.
Because of the adult’s weak and clumsy flight, Craneflies are easily caught by predators. For this reason, they can form an important part of the diet for birds and bats in autumn.
