SITTING or working in the garden is such a peaceful place to spend some time, but this is mainly due to the size of us humans.

The reasons our species has managed to occupy such a high place in the ecosystem of the earth is only partly to do with our development of language and high intelligent levels; a lot of it is down to size.

Even though it is far from hard to think of animals larger than humans are, there are relatively few animals that are sufficiently large enough to look on us as food.

If humans were just half the size, the situation would be much worse and if halved and halved again, the situation would be dire.

At this scale, a six-foot human would be just inches tall and life in the garden would not quite be so idyllic.

The main threat would come from domestic cats and dogs, the odd bird of prey and perhaps, if you were rather unlucky, a grass snake.

Once scale has been reduced that little further and you start to fall anywhere near the size of even the largest of our invertebrates things get really nasty.

The other day, I watched a cranefly blundering its way along my garden wall.

Here at least was an insect that, no matter what your scale was, would be totally harmless.

I was about to move on when I noticed that one of its legs was caught in a web that was only just bigger than the cranefly itself.

Nevertheless, the disturbance was enough to cause a spider just one-twentieth of the size of the cranefly to emerge from its retreat, a small crack in the brickwork - surely a spider this small in stature could not hope to capture a fly this size.

Unfortunately for the cranefly though, in its subsequent struggle to free its leg, the tip of its wing touched the web and the sticky silken fibres held it fast.

This was all just too much for the spider that saw this as its opportunity and it left its web and began to climb up the cranefly's wing.

This panicked the fly, whose exertions managed to throw the spider off. That's that I thought, but the spider saved itself with its useful silk and then proceeded to climb up this and onto the abdomen of the still struggling cranefly.

Clinging to the cranefly's body the spider clambered up, looking more like a parasite than a predator due to the vast size discrepancy.

I watched in morbid fascination as the spider chose a tender spot to bite again and again until the struggling of the fly was reduced to the feeble waving of a leg.

The next day I returned and, sure enough, all that was left of the cranefly was a desiccated skeleton.

Having watched the ferociousness of this battle in my garden I am so glad that humans occupy a world of such a different scale to the invertebrate.