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Photos from walk on Thursday 24th August from Stoke Row to the Checkendon area & The Black Horse pub


Penny set me a challenge to use the word stridulation in this post. Read on to see if I do.

 

Driving to the walk, I saw this:  Didcot Power Station making its own cloud.  Often seen on still days in winter when the temperature is about 4C, but rarer in summer

 

We started at Maharajah’s Well. The web is full of pictures of it, but not so many of these views:

 

The well head today.  The well’s 368ft (112m) depth is equal to St Paul’s Cathedral. Two workers dug it by hand, by turns scooping out earth and laying bricks. Its 4ft diameter proved an extremely tight workplace, and the workers faced danger because of bands of sand between layers of chalk 150ft below the surface, which tended to cave inwards.

 

The structure with winding gear was adorned by a gold-painted elephant (added in 1870).

 

Lovely beech woods, for a long while the path was well raised on either side (there must be a proper name for this)

 

And these trees at the coffee stop

 

A couple of nice bugs at coffee time. Photos are not great. Find Callomyia amoena, a species of flat-footed flies in the gallery.

 

But this next is worth a mention. Cotesia glomerata, the white butterfly parasite, is a small parasitoid wasp. When cabbages are attacked they release an odour called a kairomone that attracts a species of parasitic wasp Cotesia glomerata that then lays its virus-coated eggs in each caterpillar as a living host. They proceed to consume it, carefully avoiding the vital organs to keep it alive. At the same time as protecting the eggs and larvae from the caterpillar’s immune system, the bracovirus also manipulates its behaviour. As they emerge from its side to pupate the still-living caterpillar weaves a fine silken web over the yellow cocoons as a protection from another species of hyperparasitic wasp, living on to protect them for several more days. [Thanks @theearlybirder, and I think it was on Springwatch this year]

 

 

A somewhat dowdy Speckled Wood butterfly

 

Towards the end we crossed this grassy field and I wondered how many grasshoppers were lurking about. I couldn’t see any, nor could I hear them. They make their noise by rubbing the sharp edge of the lower wing, called a scraper, along the file of the upper wing. The vibrations caused by running the scraper along the file are the source of the cricket’s chirp. “It’s like running your thumb down the teeth on a comb”. Oh, and this way of making sound is called stridulation. Sadly, grasshopper stridulation can become the sound of silence as time goes by. The grasshoppers may still be there, you just can’t hear them any more. Grasshoppers and crickets “sing” at very high frequencies, and these can be lost as you age.

 

Back at lunch time I thought I sat down beside a pair of spiders, who sat motionless the whole time I was there. But no, there are Mitopus morio is a species of harvestman The female  is usually larger than the male and has a dark brown saddle on a pale background; in the male the saddle is blacker. So, are these two males, or a heterosexual pair:

 

They walk using their first, third, and fourth sets of legs, and use the unusually long second pair of legs to feel in front of and probe the environment.

 

Close-ups in the gallery.


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