Those that survived were suddenly free of their wings, running rapidly back towards the Wall. Whole wings were scattered all over the ground like glinting shards. The Insects trampled them heedlessly. I concentrated on one Insect alone on the river bank. It settled, took hold of its wings with its nearest pair of legs and pulled them off. They didn’t leave a wound or a scar, or any sign of the enormous muscles that must surely be driving them.

When the newly grounded Insects reached the lake they joined thousands of others all along the south shore, gathered so densely they were clambering over each other. Many were turning around, dipping their abdomens into the water. What appeared to be streams of froth drifted away from them. All around the lake margin the Insects’ tails were pushing out lines of white foam, which lazily tangled with other streams into an irregular lace, drifted towards the lake centre and became indistinct as it slowly sank in the depths.

I put some distance between myself and the chaos of the mating flight to gain a clearer picture of what was happening. Were these different Insects altogether?

The fresh perspective simply brought new questions. More Insects were swarming over the Wall and their saliva was melting the paper as if it was wax. They were working hard to pull out darker lumps from within the liquefying spit. I glided closer to see what was happening-then wished I hadn’t. The lumps were cadavers, the remains of soldiers. Free of the spit that had formed the Wall and preserved them, some were so rotten that they began to fall apart. There were horse limbs and heads, whole sheep from Lowespass farms, the feral mastiffs of the forts, and some chunks of matter I couldn’t recognise, all covered with the white paste.

The Insects carried them directly to the lake. All along its shores they were wading into the water as deep as their middle leg joint and dropping their burdens. They lowered their heads and nudged the ancient carcasses further in; I could see them bobbing, leaving ripples.

The reservoir edges were filling up with a putrid mass of sodden rotting meat. Chunks washing at the surface and at the water’s edge were releasing a thick, dark brown and oily scum that started to resemble broth. They were turning the entire lake into a waterlogged charnel pit. The amount of matter being dumped was displacing the water and the dam’s spillway glistened as shallow pulses ran down over its cobbles.

‘Oh shit,’ I said, for want of a better word. I had never seen Insects do something so complicated. What if they were sentient after all?

The rank smell of rotting fat and skin rose on the breeze, making me retch. I folded an arm over my face and gained height above it, but I knew it would stick in my sinuses for days. I took a last look at the gruesome mess and skimmed away from the lake. More Insects were beginning to build a new Wall around it.

They were ranging freely over the whole countryside, scurrying on the road, feeding on dead men and horses-and carrying fresh pieces, still dripping, back to join the corruption they had made of the lake.

I couldn’t stay there, not so close to the stench. It seemed to cling to my feathers no matter how high I flew. I winged towards the town.

High above the gatehouse I saw an Insect buzz through the hail of arrows. They found their mark and it suddenly bloomed with white flights. Shafts stuck out all over it as it passed underneath me. It went into a steep descent, wings beating furiously, and crashed into the roof of the tavern buckling all its legs. Its wings flickered; the time between each vibration lengthened until it died.

I took this as a warning-the steel crossbows mounted on the ramparts have an awesome seven-hundred-metre range-so when I was about a kilometre away from town I climbed high and came in above them.

I looked down into complete confusion. The outermost road of the three concentric squares was totally infested. Soldiers were shooting Insects from the safety of the curtain wall, the large square shutters all hooked back. Archers stood on every available rampart, crossbowmen leant out of windows, rocks and boiling water issued through the machicolations of the hoardings, bombarding the Insects directly underneath. I even saw civilians hurling roof slates into the seething mass.

From the window in the first ring of barracks, spearmen jabbed frenziedly at any Insects getting too close.

In the inner two roads and the central square, smaller numbers of Insects ran at random, claws skittering on the cobbles. Bodies littered the streets. Most of the iron paling gates had been shut across the roads. Others were barricaded with heaps of furniture, anything men could lay their hands on in the panic. Slake Cross was designed so that if a road ring was taken, we could pull back to the next one, and so on, to the middle-but that design depended on Insects attacking on the ground, from outside. The Architect could never have envisaged them dropping in from the sky.

I banked, turning in a shallow glide towards the intense throng continuing to rise into the air above the lake. Their opaque buzzing made it difficult to think and the sweeping movements of the flight were so ultimate, so terrible, it drew my gaze and I watched, hypnotised.

A shout rose over the buzzing: ‘Hahay!’

Surprised to hear an Awian hunting cry I glanced down towards the source and saw an Insect pacing me, only a hundred metres below. As I saw it, an arrow storm poured from the walkways. Enfilade shooting from the tower tops caught it in cross-volleys. It twisted in the air. Arrows slashed its wings to ribbons-it seemed to fold up and dropped like a stone, straight down, its abdomen writhing with a blind life of its own. The Insect hit the ground by the moat and splattered-great splits opened up in its carapace and its insides began to seep out, pooling yellow on the grass.

I slewed left and right in acknowledgement at the favour although in reality I was far more alarmed by the prospect of being riddled with arrows than being bitten by the Insect.

Time to show them I didn’t need their help. From what I had seen of the Insects’ manoeuvrability I was definitely the stronger flyer. I put my hand behind me, unfastened a stud and drew my ice axe from its holster fastened horizontally on my belt. I went into a glide and tapped its steel head thoughtfully against my palm as I circled the town.

I stripped off my bangles and shoved them into my coat, and buttoned my sunglasses into my inside pocket. I positioned myself above the nearest Insect, my shadow covering it. Its dragonfly-like head swivelled: it could see three hundred and sixty degrees around it. It saw me and tried to climb to my altitude, but I was far more agile. I stood on one wing and turned, soared directly over, and gave its rapidly beating wings a good solid kick as I passed. The Insect rocked, righted itself in the air and dived.

I whooped and dived after it. It wouldn’t let me stay above its head. I saw dark patches on its compound eyes that looked almost like pupils, one pair on the top, another pair facing forwards. At first I thought they were reflections, then I realised they were areas of smaller facets, set closely together. Perhaps the eyes of these mating Insects are different too; it seemed to see well directly above it. I decided to attack by coming in fast and from the side. I swerved away, turned so steeply the ground and all its towers swung up to my left. I beat with my wings close to my body and bore down on it with full speed.

The Insect saw me too late, jinked, but I rammed into its thorax, grappling so it couldn’t turn to grab me. We whirled together, losing height, and the wind stream roared up past us. The ground rotated and spun crazily. I didn’t look down, I have a sense of how close I can fall, how big the buildings can grow before I seriously start to panic. I hefted my axe and chopped through its neck. The Insect’s head detached and I let it fall but the body flew on thirty metres before tumbling to the ground.