Spanish chestnut opposite did not move, I began to realise that this
creeping, rustling noise, distinctly audible, was not caused by any
wind, but by the thousands upon thousands of insects passing over the
dead leaves and among the grass. Stooping down to listen better, there
could be no doubt of it: it was the tramp of this immense army.

The majority still moved in one direction, and I found it led to the
heap of rubbish over which they swarmed. This heap was exactly what
might have been swept together by half-a-dozen men using long gardeners'
brooms, and industriously clearing the ground under the firs of the
fragments which had fallen from them. It appeared to be entirely
composed of small twigs, fir-needles, dead leaves, and similar things.
The highest part rose about level with my chest--say, between four and
five feet--the heap was irregularly circular, and not less than three or
four yards across, with sides gradually sloping. In the midst stood the
sapling birches, their stumps buried in it, the rubbish having been
piled up around them.

This heap was, in fact, the enormous nest or hill of a colony of horse
ants. The whole of it had been gathered together, leaf by leaf, and twig
by twig, just as I had seen the two insects carrying the little stick,
and the third the brown leaf above itself. It really seemed some way
round the outer circumference of the nest, and while walking round it
was necessary to keep brushing off the ants which dropped on the
shoulder from the branches of the birches. For they were everywhere;
every inch of ground, every bough was covered with them. Even standing
near it was needful to kick the feet continually against the black stump
of a fir which had been felled to jar them off, and this again brought
still more, attracted by the vibration of the ground.