Today was an amazingly hot day for mid-March. It dawned foggy and chill, but quickly warmed up. Down at the Gunnersbury Triangle, a big pile of coppiced willow logs and some birch trunks were waiting to be built into a loggery. This is by intention a home for the stag beetle, which happens to have its British stronghold centred pretty much on south and west London. The stag beetle larvae are soft, white helpless grubs, a ready meal for a fox or a hungry bird – except that they live underground, or rather in timber which is in contact with the ground. They tunnel through the dead wood with their only really hard dark parts, their mouthparts, grow fat, split their skins and continue eating wood and tunnelling along, gradually making holes of larger and larger diameter. After some years – it can be up to seven – they metamorphose into handsome adult beetles with their black and shiny chestnut carapaces, walk or fly, mate, lay eggs in dead timber which is in contact with the soil, and die.

To accommodate this bizarre life history, we dug a trench somewhat more than knee deep – quite a feat in the sticky brown clay with some flint gravel – and packed in the logs as tight and close as we could get them.

We then jammed short lengths of smaller wood in between the logs to prevent them from wobbling, and finished up by shovelling earth and clay into all the gaps and stamping it well down.

The rest is up to the beetles – millions of years of evolution has given them a superb ability to find suitable places to lay their eggs – and then with luck in a few years’ time we will see some shiny new stag beetles walking heavily about the reserve.