Common darter dragonflies laying eggs

A couple of weeks ago I watched these two common darter dragonflies, coupled together in tandem, laying eggs in a shallow pool near Hawthorn dene on the Durham coast. I'll be keeping an eye on it, whenever I pass by, to see how well the nymphs are developing. 

It may be a race against time for them, because these shallow pools on the limestone dry up completely in early summer in years when there is a drought. They dried up for several weeks this year, and last. 

I imagine that their success will depend on how the rest of the aquatic fauna, their food source, develops over the next few months. If frogs or toads lay eggs in the pools in spring, as they sometimes do, then the nymphs will have plenty of tadpole food and might complete their development and hatch as adults in less than a year, which they are capable of, if conditions are good.

While I was watching these two I noticed that they were attacked, unsuccessfully, several times by a much larger southern hawker - the first time I've ever noticed a display of aggression between dragonfly species.

 

A butterfly haven in an old limestone quarry

This is Ashes quarry, a former limestone quarry near Stanhope in Weardale that is now a wonderful nature reserve. The quarry floor is partially flooded and is a breeding place for dragonflies and damselflies, but this sheltered western end, which is mostly rough grassland and quarry spoil heaps, is always a good spot to look for butterflies.

It was good to see a small colony of wall browns has become established here. This is a butterfly that needs warmth and shelter, so this sun-trap, with its sun-warmed rock, clearly suits it very well.

Wall browns are very skittish insects, never settling for long in one place. This individual alternated between basking on its pile of rocks and feeding on herb robert flowers blooming amongst the stones.

The convenient supply of floral nectar meant that this one was constantly disturbed by rival males that tried to take over its domain. Wall browns are ferociously territorial, so each one of these incursions resulted in an aerial dogfight, as the butterflies spiralled upwards, so close to me that I could hear their wings clashing, before they separated and fluttered back to their respective territories.

Eventually a female arrived and courtsship began, with the pair walking through the grass and the male tapping the female with his antennae. I think the male is the closer of the two in this picture, with some wing edge damage that might have occurred during one of those bruising dogfights with a rival.

Wall brown colonies tend to be small and don't often persist in the same place for long, but this quarry site is sheltered and warm, with plenty of the caterpillar food plants (grasses), so it might last for a few years.

The warm piles of stones in the quarry are also excellent habitat for sun-basking common darter dragonflies ....

..... chirruping field grasshoppers Chorthippus brunneus

..... and this devil's coach-horse Ocypus olens. This beetle (more pics here) isn't often seen out and about in bright sunlight - it's more often seen in twilight.

Tandem dragonflies

We spent a fascinating afternoon recently watching dragonfly behaviour at Ashes quarry at Stanhope in Weardale.

The most numerous dragonflies in the shallow, moss-edged pools there are common darters, Sympetrum striolatum. We watched them on their egg-laying flights, where the male tows the female around, attached by the tip of his abdomen to a point just behind her head.

Coupling up like this is the male's way of defending the female he has inseminated, preventing rival males from mating with her and displacing his sperm.

It's an unwieldy arrangement. At frequent intervals the male lowers his abdomen, forcing the female down to the water surface where she drops fertilised eggs from the tip of her abdomen.

That's an awkward manoeuvre, when the male momentarily hovers in this vertical position.

The males are fiercely defensive of their territory, often perching on a favourite stone or ....

... plant stem, ready to drive off rivals and pursue any passing female.

The second commonest dragonflies at this site are black darters Sympetrum danae. There seemed to be quite a lot of interspecific aggro - we watched several aerial battles between the two species.

These dragonflies land with their wings outstretched but ....

... finally come to rest with them in this swept-forward configuration.

Thursday's Guardian Country Diary is about this male common darter dragonfly - surely the last of the year - that we saw a few days ago on the banks of the river Tyne near Wylam. 

It settled amongst the fallen autumn leaves and seemed very reluctant to move away from the large patch of flowering ivy that still attracted flies that it was probably feeding on.

Since then we've had some hard frosts. It will be eight months before we see the next generation hatching out.