Tuesday 15 October 2019

Grasshoppers' chirping sound a mating call

A Common Field Grasshopper sunning itself. While often brown, colours and markings vary greatly
A Common Field Grasshopper sunning itself. While often brown, colours and markings vary greatly

Jim Hurley - Nature Trail

For the nature enthusiast, one of the many evocative sounds of high summer is the chirping of grasshoppers. The Common Field Grasshopper is one of our most common and widespread, so it is probably the species most readily associated with chirping heard at this time of year.

Chirping is often heard during a summer excursion to the seaside as many grasshoppers prefer the short, dry grassland habitats found near our coasts. In addition to 'grass' being part of their common name, these insects are referred to as 'hoppers' because of their ability not alone to hop but to jump impressively.

Both jumping, and chirping are achieved by the insects' well-developed hind legs. As shown in the image above, the hind legs are very long and muscular. The length and muscles aid jumping and hopping, and it is a series of tiny pegs along the hind legs that produce the chirping.

The tiny pegs on the hind legs protrude like the teeth on a file.

Grasshoppers are strong fliers. They have four wings. The hind wings are soft and membranous while the long fore wings are hardened cases with prominent, toughened veins.

The chirping sound of the grasshopper's song is produced when the insect rasps the tiny, file-like pegs on the hind legs against the prominent, toughened veins running along the fore wing cases. The sound is reminiscent of that produced when one draws the teeth of a comb across the top of a finger nail. Both males and females chirp.

A male seeking for a mate will perch on a stalk of grass and chirp. He produces a song using five to twelve different notes. Each chirp lasts about half of a second. Nearby rival males may chirp in reply and a chorus of chirping may follow as males try to outdo each other in a sonic competition to impress any females within earshot.

If interested, a female responds by signalling her receptiveness to a male of her choosing by singing a similar-sounding song to that being sung by him.

Fertilised females will lay eggs in the soil. All of the adults will die with the onset of next winter and the species will survive over winter as unhatched eggs lying dormant in the soil.

All going well, next May the eggs will hatch, and a new generation will emerge to produce the adults that will be chirping at this time next year.

Wicklow People