HOUSE GUESTS

Whatever the rights and wrongs of thinking we are somehow separate from other life forms, there is one place where we’d like to have things entirely on our own terms. Wildlife tends not to be welcome inside our homes.

Before we moved to rural mid-Devon, I don’t think I’d heard of this creature. Now it provides us with a major source of irritation from August well into the winter, if the weather stays mild. At first, we notice them starting to gather on the white­washed outside walls, mostly on the warm, south-facing side of the house. Then the assault begins. Small numbers gather in the slender gaps between the windows and their frames, secreting themselves out of sight and away from predators, lying in wait until someone swings open the window, when they flop drowsily into the room, and sometimes into your face. It looks very much like a typical House Fly, but this beast is the Cluster Fly, distin­guished by a mat of golden hairs on its thorax and its propensity to huddle together with others of its own kind for the winter.

These window-frame Cluster Flies are a minority. The real swarming masses target the conservatory, finding their way in through a tiny gap where the highest point of the structure is attached to the house. The gap has been plugged perhaps half-a- dozen times, on each occasion with limited success.

In the sunshine, when the conservatory warms up, they buzz incessantly and blunder hopelessly against the windows. The space is all but uninhabitable for humans seeking tranquillity and comfort. But as the sun fades in the evening and the air cools, they become inactive. Only then does the name begin to make sense. They gather in tightly packed groups in the corners of the windows and on the walls, where they will see out the night. This is a clue as to why they enter the house in the first place. They are looking for a secure, cool and sheltered place to overwinter. A loft is perfect, and tens of thousands find their way into ours - to remain there through the coldest months.

Those that choose the conservatory find a place subject to extremes of temperature and soon die.

The small numbers that make it into the house have escaped from a whole suite of potential predators outside, but they are far from safe. The main threat comes from irritable humans armed with a vacuum cleaner. We feel guilty for employing such a heavy­handed approach, though reading about their life history helps to assuage this a little: in spring, any survivors will head outside to lay who knows how many eggs in the soil, and the resulting larvae will parasitise earthworms. Meanwhile, there are natural predators on the inside too. The much-feared (by flies and humans) Giant House Spider patrols the floors at night, retreating by day to its sticky traps in undusted corners. If a fly strays into a web its prospects for seeing out the winter will be greatly reduced.

I’m not a certified arachnophobe but the autumn sorties of this spider across the carpet do make me a little uneasy, especially in the bedroom.

I was surprised to learn that House Spiders themselves are vulnerable to becoming spider food. We have lots of spindly Cellar Spiders, or Daddy Long-legs Spiders as they are often called. They are present in most rooms, lurking in corners and along the edges between wall and ceiling, building loose, ramshackle webs and, for the most part it seems, doing precisely nothing. Every so often a female produces an egg sac, out of which hatches a cluster of tiny spiderlings. There may be several dozen in each brood, though all will have dispersed within a few days. I often wonder where they all go.

The adults look unthreatening, with their tiny bodies and long periods of inactivity, but don’t be fooled. In our old house I once watched a battle unfold between a Cellar Spider and a House Spider of similar size. The Cellar Spider darted back and forth, throwing a tangle of threads at its rival and quickly immobilising it. Once restrained, it became easy prey. A single bite - and then a prolonged embrace as its insides dissolved and disappeared into the victor.

While my wife, Hazel, has nothing but bad things to say about Cluster Flies and their annual takeover, I can at least point to one significant benefit. As well as providing food for spiders, they are also much sought after by insectivorous birds. In early autumn, the house begins to attract fly-eating species. Wagtails are pre-eminent in the mix.

Less often, we are visited by a lone Grey Wagtail. These are such lovely, elegant birds, with bright lemon-yellow underparts set off against black, white, and subtle powder-grey on the back and head. They are slimmer and more refined than their black- and-white relatives, with an even longer tail. They too loiter around the house, parkouring over the roof and along the window ledges. Once, I managed to sneak up on one that had alighted on the narrow ledge just outside the landing window. Peering through the glass from inside, I needed my reading glasses to focus on it. We watched each other for a few moments - me stock still and holding my breath; the bird living up to its name, pumping its tail while trying to decide whether I was a threat.

We’ve seen another bird taking advantage of the flies, one that ranks a notch above the Grey Wagtail on two counts. It outscores the wagtail on rarity value. And this particular individual went one better than resting on a ledge just outside the house: it managed to get in. It was late evening. I’d gone to open the back door to let the cat in from our adjoining, open-fronted garage. In pottered our black cat, and at the same time, almost grazing my head, in shot another black creature. It darted straight into the downstairs toilet. I turned on the light and could barely believe that I was looking at a Black Redstart. It must have been roosting in the garage. We’d seen an individual around the house the previous autumn, catching flies on the patio, but to have one inside the house was something rather special. I caught it in my hands as gently as I could and released it back into the garage.

The Swallows that nest in the garage, and the House Martins under our eaves also take advantage of the abundant insects, skimming just above the guttering, picking off unwary flies. In some years both these birds still have young in the nest into late September, but soon they will all head south, and fuel for the long trip ahead is no doubt very welcome. Even the garden Blue Tits snatch the odd fly while they wait on the gutter of the garage for their turn at the feeders.

I’ve also seen Hornets try to catch flies around the garden, using a technique that contrasts starkly with the madcap chases of the wagtails and the graceful elegance of the hirundines. The Hornets spot potential prey and smash straight into it, while trying to envelope it in their legs. Perhaps their eyesight is poor, because I sometimes see them doing this to the small tufty flowers that emerge from the Soft Rush stems growing in damper corners of the lawn. They crash into them, testing to see if they are prey before realising their mistake and quickly moving on. The same approach works well enough with flies, though usually only the drowsiest are vulnerable. This may help to explain why Hornets remain active at dusk and even into the night, when the air cools and most insects become far less alert and mobile.

One year, Hornets took over a bat box hung on the telegraph pole at the edge of the garden. This made venturing outside somewhat hazardous. The box was only a couple of metres above the ground, and the worker Hornets transiting to and fro would arrow past on flightlines at about head height. I feared I might swallow one by mistake if my mouth was open at the wrong time. Then, at night, they would try to enter the house, homing in on the windows of lit rooms, tapping menacingly against the panes as if asking to come in. We soon learnt to keep the windows closed after dark, and we would watch as many as six of them together, crawling up and butting against the glass. Just a few millimetres between our protected human domain and everything else beyond.