The Spiders and The Fly

Today's Guardian Country Diary describes a walk along a stretch of the banks of the river Wear at Wolsingham in Weardale, along a footpath known as The Fly. The name probably refers to the fact that this is a good stretch of fly fishing river, but it's also a fine place for finding interesting insects and spiders.

The early part of the walk passes through meadows like this one, which have produced a wonderful display of buttercups this year. This might be because the buttercups, which store starch in their roots over the winter that can be used for rapid growth in spring, have responded to the unusually late spring by growing more rapidly than the grasses.

Then the path plunges into shady woodland with dense vegetation on the edge of the river .......

... before the trees - mostly alders along this stretch - thin our. At this point the soil is mainly fertile silt left by winter floods and the vegetation is luxuriant - these aniseed-scented sweet cicely plants were head-high. If you click here you can see what this spot looked like back in May, when the tallest plants were only ankle-high.

A crane-fly, showing the paired balancing organs rather nicely.

There were a many of these snipe flies Rhagio scolopacea (above) lurking in the last of the hawthorn flowers that bloomed almost until the end of June in the hedgerow along the first part of the path. They're predators, flying out to catch passing insects. Snipe flies have a distinctive habit of resting in this head-down posture in hedges. Those unusually large eyes are exceptionally sensitive to movement of prey passing through their field of vision.

The dense riverbank herbage is perfect habitat for these scorpion flies Panorpa communis. The curled up tail, which looks dangerous, is really the male's specialised genitalia.

Scorpion flies belong to a very ancient order of insects called the Mecoptera and fossils of their distinctive wings show that they evolved at least 250 million years ago. They are thought to be the ancestors of butterflies, moths, caddis flies and true flies. 

The two pictures above are of a female, which lacks the 'scorpion' tail of the male.

Bird cherries are a prominent component of the tree flora here and some have become infested with small ermine moth caterpillars, which weave a silken tent where they can defoliate the tree in comparative safety ....

... although this one has broken cover.

In years when there are heavy infestations whole trees can be enveloped in these silk tents.

There's a diversity of fly species along this footpath - and also plenty of spiders. The three pictures above show the cucumber-green Araneus cucurbitinus, whose abdomen can look like a flower bud. It weaves its snare across the surface of leaves.

This, though, was our most fascinating spider discovery - a ball of recently hatched diadem spiderlings (aka orb web spider, aka garden spider) Araneus diadematus. At this stage they huddle together for mutual security but if you give this seething mass of tiny arachnids a gentle poke .....  

...... the spider-ball explodes and they scatter in all directions.......

... racing away along the silken threads that suspend the ball ....

.... like sailors climbing the rigging of a sailing ship.