Flying Ant Day

The fourth heatwave of the year arrived, the temperatures soared and the ants in one of the garden waste recycling bins took to the air in vast numbers. 

For the second year in a row ants have nested in a black 'dalek' compost bin, many of them visiting the near-by cardoon plant in July to collect honeydew from a spectacular aphid infestation. Today was the day when the temperature inside the bin triggered the emergence of a new queen, pursued by the mating flight of hundreds of large winged males.
 

Semaphore flies, with a language all of their own

 There are scores of these colourful little semaphore flies in the garden at the moment, performing their highly entertaining courtship rituals, which involve a lot of wing-waving.

Poecilobothrus nobilitatus is small but exquisite, 7mm long, with emerald eyes that burn with inner crimson fire in the sun, a bronze body shot through with green and purple iridescence and, in males, white spots on the wing tips.

The male semaphore fly’s courtship dance follows a predictable pattern. He spots a female  and a brief aerial pursuit ensues, performed with such speed and agility that it is impossible to follow with the naked eye. She settles again and he lands in front of her, white wing tips whirling in a frantic effort to semaphore his intentions, often met with total indifference. Usually, she continues to feed, rarely turning to face him. I have watched these rituals many times, and have yet to witness a successful mating. 

Sometimes two males, like those in the picture above, will face one another and, apparently, attempt to intimidate each other by vibrating their wings - but who can tell exactly what these rituals mean? Only Poecilobothrus nobilitatus can really decode this semaphore signalling language.

Sometimes the flies adopt this head-down, tail-up posture but they rarely stay still for long.

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Nursery web spider

 The rough grassland on the old Brancepeth  colliery site, never grazed or mowed, is perfect habitat for the nursery web spider Pisaura mirabilis. This female had recently enclosed her egg cocoon inside a silken tent woven around grass stems - a nursery where the vulnerable spiderlings can hatch and grow in safety.

Over 250 years ago, the Swedish taxonomist Carl Alexander Clerck gave this species the scientific name Pisaura mirabilis, the marvellous Pisaura. Its fraught courtship ritual has been a source of wonder for arachnologists ever since. Males pacify females, which are notoriously prone to cannibalism, with the gift of a fly wrapped in silk. The larger the fly, the longer it will take to unwrap and eat, extending the opportunity to copulate before her hunger turns to aggression. So, there is a premium on males who are good hunters, though deceitful suitors sometimes wrap and present small twig fragments, risking death mid-copulation when she uncovers the fraudulent offering.

If she does accept his advances she'll eventually produce a ball of eggs wrapped in white silk that she carries in her jaws, slung under her body, until they are almost ready to hatch. The egg cocoon is so large that she is forced to walk around on tip-toe, to keep it clear of the ground.

 These pictures show what happens next - a remarkable example of spider maternal instinct. Her eggs have matured and the grasses have grown tall, so she climbed to the top and bound a few together with silk. Then in the space below she wove a tent, deposited her eggs inside, nibbling through the cocoon so that the spiderlings could hatch and then finally sealed them inside their silken nursery. 

Now, she’ll stand guard until they grow large enough to bite their way out of their nursery and take their first steps into the outside world. In the photographs below you can see her yellow egg cocoon, safe inside the nursery she has woven, with spiderlings beginning to hatch.