Exploring the undergrowth

I spent a couple of hours last week, on a warm, humid afternoon, exploring the undergrowth at Deepdale Nature Reserve in Barnard Castle. The boggy ground on either side of the footpath was overgrown with butterburr leaves, meadowsweet, vetches, red campion and docks and was seething with insects and spiders.  These are a few that I managed to capture on camera. 

Earwig  - for more about earwigs click here

Female scorpionfly

Male scorpionfly - for more about scorpionflies click here

The beautifully iridescent green dock leaf beetle  - for more about this species click here

A sawfly that I haven't managed to ID for sure yet - for more sawflies click here 

A spider, Tetragnatha extensa, with a golden abdomen. For more spiders click here.

A very bug-eyed mayfly - possibly Ephemera danica. For more on mayflies click here.

A common green capsid bug Lygocoris pabulinus - for more on capsid bugs click here

A staphylinid beetle stretching its wings....

..... curling up its tail in characteristic defensive mode ....

..... and with its wings packed away, showing the extremely short wing cases. For more staphylinid beetles click here

Here Today, Gone Today......

This mayfly landed on the spokes of my umbrella when we were out walking by the river Tees in the rain at the weekend and walked through a mating swarm.  When mayflies hatch from their aquatic larvae they often appear in very large numbers and there are  swarms along most of our local rivers at this time of year. Mayflies are weak fliers, merely dancing up and down in the air, and the main purpose of their flight is courtship. The males wait for females to stray into the swam, then grab them and mate with them in flight. We watched several successful 'captures' with the pair locked together and falling out of the air into the vegetation below.

Once the male’s purpose is fulfilled the females head for water, fluttering just above the surface to lay eggs  - and so providing a feeding bonanza for trout that leap to catch them. Those that escape the attentions of fish are often snapped up by swallows skimming across the water. The life of an adult mayfly can be over in a single day, lasting just long enough to produce eggs that will perpetuate the species.

I haven't identified this species yet but it does have this distinctive pale blue eye stripe.

A second slightly different mayfly, possibly the same species but the other sex, landed into the umbrella.


More pictures of mayflies here.

Tales from the Riverbank....

Many of the rocks along the banks of the upper reaches of the river Wear carry the empty nymphal cases of stoneflies, recognisable by the paired tail filaments. The split in the thoracic segments marks the point where the adult insect eased its way out of the nymphal exoskeleton after the nymph crawled out of the water.

Stoneflies tend to be confined to fast-flowing, well oxygenated, unpolluted rivers, which is a pretty good description of this stretch of the river Wear between Wolsingham and Black Banks, in Weardale. Currently, after a long spell without heavy rain, the water level is low and mayflies are laying eggs in the shallows and pools.

Mayflies are the only insects that moult in their adult stages. The winged adult that emerges from the nymph is the subimago (known to anglers as a 'dun') and this undergoes a final moult to become the imago ('spinner' in angling parlance). This is an imago that appears to be laying eggs, and drowning in the process. Females have shorter front legs than the males.

Mayfly nymphs have three tail filaments but the adults can have two or three tail filaments, depending on genus. The hind wings in mayflies are much shorter than the forewings....

.. and both pairs are held vertically above the body when at rest.

There are two large compound eyes and three small ocelli in between them. Adult mayflies do not feed during their short lives, so there are no functional mouthparts.

Male mayflies are notable for their extremely long front pair of legs, which are used to grasping females during mating flights.

During emergence and mating flights low over the water surface, vast numbers fall victim to fish - especially leaping trout - while those that survive fish predation ...

....become food for birds like dippers, which also feed on the nymphal stages of stoneflies and mayflies.