Two down, seven to go.
There are still two missing.
All present and correct.
But they won't be safe until they reach water.
And the forest pool is almost a mile away.
By June, the days are at their longest
and all across the northern hemisphere the broadleaves are hard at work.
On the east coast of North America, it seems like any other summer's evening.
But tonight is special.
After 17 years underground, creatures are stirring.
The nymphs of the periodical cicada have been biding their time.
Now they march like zombies towards the nearest tree and start to climb.
At first there are merely thousands.
But soon more than a billion swarm all over the forest.
The biggest insect emergence on the planet is underway.
They invade the upper branches where they climb out of their external skeletons
and assume their adult winged form.
At first, they're white and soft.
But they have until dawn to complete their transformation.
After an absence of 17 years, the forest is now overrun by cicadas.
The adults are clumsy and very edible.
For turtles and other inhabitants of the forest,
this is a feast they're lucky to see once in their lifetime
and they gorge themselves while they can.
Times have never been so good.
The cicadas have no defences and virtually offer themselves to their attackers.
The stream of insects is so relentless
that soon all the predators are full to the point of bursting.
And still the cicadas come.
With the predators overwhelmed , the survivors can achieve their purpose.
After mating, the adults lay their eggs and then their job is done.
In just a few days they will all die and the forest will fall silent.
The cicadas here will not be heard again for another 17 years.
Having fed the predators, the cicadas leave one final gift for the forest itself.
The nutrients in a generation of cicadas are returned to the soil all at once.
And the trees enjoy a marked spurt in growth.
This may be the single largest dose of fertiliser in the natural world.
In the great broadleaf forests of Eastern Europe,
the days are beginning to shorten
and a primeval sound heralds the onset of autumn.