Ants in the compost bin

 We've been composting garden and kitchen vegetable waste in 'Dalek' bins like this for decades, but this year was the first times that we've had one taken over by nesting black ants. 

They moved in during those unusually cold weeks of early summer, probably because the warmth of decomposition in the bins provided the only location in the garden with enough heat for them to breed.  Textbooks say that they need a temperature of 10C to become active and 20C to raise a brood.

Watching their progress in the bins has been fascinating because the temperature inside rises very rapidly when the sun comes out and falls equally rapidly on dull wet days and in the evening, so they seem to be constantly moving their brood around to the optimum positions in the bin. At one point I thought they had left, but it seemed that they just moved their larvae and pupae deeper into the compost, in a cooler part of the bin. They shift their brood with remarkable speed when I lift the lid and light floods in - they can move a couple of hundred pupae, by carrying them in their jaws, in a few minutes.

Their larvae are translucent, but as they  pupate they spin a silken coat.

Lately, winged males have started to hatch so before long a queen will take to the air, followed by a swarm of males on the nuptial flight. After mating she will start a new nest, while most of the males will become food for swifts that swoop over the garden. 

More tales from the compost bin: millipedes

Another player from the cast of thousands whose daily dramas are played out in our compost heap - in this case ....

.... a flat-backed millipede Polydesmus angustus, going head-to-head with a springtail. Flat-backed millipedes feed on rotting plant material so the springtail isn't under serious threat...... unless it's about to be trampled by a large number of feet.

Flat-backed millipedes are very good climbers - this one climbed the near-vertical outer wall of the plastic compost bin with no difficulty.

I made my excuses and left ........

The compost bin at the bottom of our garden recycles all our vegetable-based kitchen waste and every time I lift the lid it reveals a new population of animals, most of them small ........

.... like this hairy little owl midge, about three millimetres long. 

This minute juvenile woodlouse, also just a few millimetres long and looking like it's not old enough to be out on its own, was lurking under the bin lid. To give some idea of how small it was, compared with a full-sized woodlouse ....

........... here's a slightly larger juvenile (about three times the size of the one above), under the watchful compound eyes of a full grown woodlouse.

The prize for the most numerous insects in the compost bin must go to these minute flies, smaller than the owl midges, that breed with amazing speed and in incredible numbers on the decaying fruit and vegetable peelings. Every time I lift the lid I have to step back as a small cloud of them takes to the air. I rarely see singleton flies of this species, because they seem to be ......

.... perpetually mating, in this push-me-pull-you conformation.

When I was a callow youth I used to frequent a barber's shop where they always had a pile Reveille and Tit-bits magazines for customers to leaf through while they waited for a trim. For those unfamiliar with these fine publications (long-since defunct),they specialised in 'tasteful' glamour photos of ladies who seem to be having trouble keeping their clothes on, together with sensational and highly improbable stories (of the 'My ordeal amongst cannibals' variety), Daily Express style editorials about the country going to the dogs ('What has happened to our national pride?) and investigative journalism that lifted the lid on the licentious behaviour of the ruling classes. The latter always involved intrepid undercover reporters visiting sordid establishments in Soho, witnessing goings-on that mostly seemed to involve clergymen, Members of Parliament and burlesque dancers ..........

.......... engaged in this sort of activity. 

The pay-off line for such stories was almost always "disgusted, your reporter made his excuses and left". 

Which is what I did after I lowered the compost bin lid on these three and plunged them back into darkness.

Getting a grip..

We've got three black compost bins in the garden that recycle most of the garden waste and all of the plant-based leftovers from the kitchen, so they provide a constant source of compost for the soil. The animals in the bins that do much of the recycling work are these brandling worms Eisenia foetida, aka tiger worms, aka European nightcrawlers.

A curious feature of these worms, apart from their rather attractive tiger stripes, is that they often climb the sides of the compost bins and can easily scale vertical surfaces, often attaching themselves to the inside of the bin lids. 

If you take a look at the next picture you can see how they climb .........

Each segment of an oligochaete worm like this bears stiff, retractable bristles called chaetae, which are the little white projections that you can see in the picture above. The moisture on the worm's body makes it naturally slightly sticky, but it's these bristles that grip surfaces as it alternately extends and contracts its body as it moves forward. 

In the picture above the worm is contracting the longitudinal muscles in the front part of its body so that it shortens and becomes fatter, dragging forward the segments behind whose chaetae have temporarily retracted. 

Next the chaetae on the forward segments will retract as their circular muscles squeeze them and make them longer and thinner, stretching forward, while the bristles in the segments behind will extend their chaetae to provide grip.

If you place one of these worms (or a common earthworm) on a sheet of paper and listen carefully you can hear the scratching of the chaetae on the paper as the worm wriggles.