Grasshopper

On a recent walk over Barlow Hall Tip (the area between Chorlton Golf Course and Chorlton Water Park) I spotted this grasshopper sunning itself on a lump of concrete. I am fairly certain that it is a Common Field Grasshopper (Chorthippus brunneus). This sighting reminded me that I know very little about grasshoppers, nor about their status in the Mersey Valley.

I seem to recall from my childhood (admittedly in Peterborough – not South Manchester) that grasshoppers were very common in the summer months and one could hear their ‘songs’ (stridulations) even in my parents’ suburban garden. Several questions occur to me:

· Were grasshoppers always more common in Peterborough than in South Manchester?

· Were they once commoner in South Manchester but have declined in numbers in recent times?

· Have their numbers declined everywhere?

I suppose another possibility is that, due to my advanced age, I can no longer hear them – just as I can no longer hear bats. But bats’ echo-location sounds are very high pitched (at the edge of audibility for a young person with good hearing) and I wouldn’t have thought that grasshopper songs were anything like that sort of high frequency. Perhaps I’ve just, somehow, ‘tuned them out’; next time I’m in a suitably grassy place, on a warm day, I’ll listen out for them.

The stridulations, by the way, are produced by the insect rubbing its back legs against its wing cases. Small pegs on the inner surfaces of the legs are thus dragged across the stiffened edges of the wings and give rise to the sounds. Apparently, in many species, both male and female insects can produce these sounds but the males stridulate more than the females. Needless to say the sounds have a number of functions but are mainly connected with mating.
Does anyone out there have any more information about grasshoppers – especially about grasshoppers in the Mersey Valley?

Going back to the photograph above, you may have noticed something that I missed whilst taking the picture. That is the spider which appears to be creeping up on the grasshopper from the left hand side of the block of concrete. Was this spider hunting the grasshopper? Have I inadvertently captured a scene from a ‘mini-drama’? Apparently spiders have been observed preying on grasshoppers “but information is very sparse”. Grasshoppers themselves are vegetarians and feed mainly on grasses, by the way.

Anyway, for me, the scene above evokes some sort of ancient fable – in which the wily grasshopper outwits the fierce spider, perhaps?

Dave Bishop, August 2009

Reference:

‘Naturalists’ Handbooks 2: Grasshoppers:’ by Valerie K. Brown, Cambridge University Press, 1983.