A Buzz in the Meadow (15 page)

I put the robotic beetle at the centre of the arena and began placing males on the edge. Whenever one drummed, I would reply immediately and, as far as I could tell, the beetles were completely fooled into thinking that the reply came from an eager virgin female. If the male was initially sleepy or inactive, a couple of drums from the robot usually stimulated it into life. In this way I could see how good the males were at finding the ‘female'. It soon became clear that they were pretty hopeless. They would wander around, drumming their heads and listening for a reply, often taking hours to approach the location of the robot. I filmed their behaviour and spent many hours recording their tracks, in an attempt to discern any kind of pattern.

The answer turned out to be fairly straightforward and unexciting. When a male beetle is getting replies from a female, he tends to walk a short way and then drum his head again. He listens carefully to the reply. If it is louder than the previous one, he knows he is going in roughly the right direction, and so he keeps going, pausing at intervals to repeat his call. If he is going in the wrong direction, her reply will get quieter – when this happens, he tends to turn round and head back the way he came. If she stops replying entirely (suggesting that he has walked so far from her that she can no longer hear him), he tends to turn round and go back. By this very crude mechanism, he should on average get slowly closer to her. I wrote this up as a scientific article and sent it off – my job was done. But I still had a few weeks of funding left, and I had become intrigued by something else.

When a male finds a real, virgin female he invariably clambers straight on to her back and attempts to mate with her. The males are not very bright, so they often climb on to the female backwards (to be fair, the front and back ends of the female don't look much different). He encourages her to mate by continuing to drum, but now of course he is whacking his head against the back of the female's head or, if he is the wrong way round, against her backside – an interesting form of foreplay. At the same time he extrudes his genitalia and probes away hopefully. The interesting (but perhaps not entirely surprising) thing is that often this less-than-subtle approach is not successful. Mating can only happen if the female is willing, because she also has to extrude her genitalia from under her carapace. If she refuses to do so, there is nothing the male can do about it, but continue to drum away and prod at her with his penis. If this doesn't get him anywhere, after a few minutes he usually gives up and wanders off to find a more obliging female.

I noticed fairly quickly that the larger males were more likely to succeed in charming a female than the smaller, weedier ones. I took to weighing the males before and after mating, and discovered something that seemed quite astonishing to me. On average, during copulation the males were transferring 13 per cent of their body weight to the female, and up to 20 per cent in some extreme cases. Exactly what the material was that was being transferred I never found out, but presumably it was sperm and associated juices. This is roughly the equivalent of a human male producing fourteen litres of sperm in one go – not an entirely pleasant prospect. Large male beetles tended to produce more, so by choosing the heaviest males to mate with and rejecting the small ones, the females were ensuring that they received particularly large packets of sperm. Why might the females do this?

It is not uncommon in other insects for males to transfer nutrients to the females during mating, as well as sperm. In some creatures, such as hanging flies and scorpion flies, the male catches a prey item and uses it to persuade the female to have sex with him, a so-called nuptial gift. The larger and more impressive the prey item, the more likely she is to be impressed. In some crickets, the male impregnates the female with sperm during mating, but also glues a large, sticky ball of nutritious gloop to her bottom, which she promptly eats. In all of these cases the food helps the female to produce more or larger eggs, which with luck will be fertilised by the male, so the nutrients go to benefit his own offspring. This nuptial gift might be particularly important in creatures like death-watch beetles where the adults don't get to feed much, if at all, so the females have no other source of nutrition. In this situation it might be vital for the female to choose a male that could provide the most nutrition, since this would help her to produce the maximum possible number of offspring. Obviously female death-watch beetles get an excellent opportunity to judge the weight of a potential mate when he is sitting on top of her, whacking her in the back of the head.

I experimented with playing tricks on the females. I found that I could fool a female into mating with even the smallest and weediest male, simply by putting a bit of Blu-tack on his back. The Blu-tack made the male heavier and that was all it took, although the poor female then received a most disappointing package.

One interesting side-effect of the large nuptial gift produced by male death-watch beetles is that it makes them weigh substantially less than they did before, which in turn makes them much less attractive to females. Even the biggest male could rarely persuade a female to mate with him if he had mated before, however hard he tried. The only way I could make him appealing to females was once more to make him heavier with a blob of Blu-tack. And once again the females must have felt short-changed, because whatever was being transferred to the female, the male could produce very little of it when he was mating for the second time. So it seems that in natural situations most male death-watch beetles probably only ever get to mate once, and then they have shot their bolt – unable to seduce another female because they weigh too little.

Eight years after I discovered death-watch beetles at Chez Nauche they are still there. They are slowly chewing through the timbers in the living-room ceiling, but they are huge old timbers and my guess is that it will take them at least another hundred years before they do any serious damage. I could inject the timbers with insecticide, but I haven't the heart to do so. These beetles have probably been there since not long after the house was built, 150 or so years ago, so who am I to evict them? There are few enough places left for these intriguing little creatures to live out their slow-paced lives, and in any case I would miss the sound of the Devil impatiently tap-tap-tapping his fingers.

CHAPTER NINE

The True Bugs

5
April
2011
. Run:
38
mins
26
secs. People: none. Dogs:
8
. The sneaky spaniel was lying in wait, and nipped my ankle before I saw the blighter coming. Butterfly species: just
7
, a poor haul today. However, the lack of butterflies was easily made up for by spotting my first golden oriole – what a spectacular bird, so colourful it seems like an escapee from a zoo. As I ran by I unwittingly flushed it out from some elm bushes on the side of a farm track, but it briefly settled in an oak further down, so I got a reasonable look at it. A male in breeding plumage, the size and shape of a large thrush, but golden-backed with a black mask – a wonderful creature.

It is amazing what a lot of insect life goes on under your nose when you have got it an inch from the earth. I suppose it goes on in any case, but if you are proceeding on your stomach, dragging your body along by your fingernails, entomology presents itself very forcibly as a thoroughly justified science.

Beryl Markham,
West with the Night
(1942)

Every time I arrive back at Chez Nauche after any time away the place is overgrown, the path to the front door impeded by waist-high vegetation, and one of the first jobs I have to tackle is hacking down the foliage. In late spring this invariably disturbs scores of pairs of firebugs, chunky, flattened red-and-black bugs, which spend much of their lives as adults locked in endless copulation. For reasons best known to themselves, they seem to regard the area near my door as a prime location for their sexual activities.

I use the term ‘bug' advisedly. It is of course a word that is widely used to describe any small creature, but to an entomologist it means something much more specific. Bugs, or ‘true bugs' as they are sometimes called, in an attempt to avoid confusion, properly belong to one group of insects, the Hemiptera, a collection of creatures that for the most part do not trouble humans much or attract our attention. A few of them are pests – for example, greenfly and mealy bugs – but most live out their lives quietly in meadows and woodlands, feeding on plants or other insects. There are more than fifty species in the meadow at Chez Nauche, including froghoppers, shield bugs (known as stink bugs in the US, for their unpleasant defensive secretions), assassin bugs, whitefly, scale insects and many others. In the pond there are still more: backswimmers, water boatmen, pond skaters and water scorpions (not scorpions at all, but so named because they have a long tail – in actual fact the snorkel through which they breathe).

Although they are a diverse group, all true bugs have one thing in common: their mouths are shaped into a sharp, flexible tube that can be stabbed into their chosen food and used to suck out the juices. Some, such as aphids, use this to suck on plant sap, while others such as the pond skaters and assassin bugs suck the juices from other insects, draining them dry and discarding the empty husk.

Firebugs are not unusual among the true bugs in their enthusiasm for copulation. Many bugs stay bound together for days, with the male and female facing in opposite directions, but joined by the tips of their abdomens. Movement is difficult, and when they are frightened by my weeding and strimming they try to run in opposite directions, with the bigger, stronger female usually getting her way. They remain locked together for the same reason as the dragonflies: the males are trying to ensure their paternity by preventing their partner from mating again. The females may have little choice in the matter, but perhaps have no strong incentive to escape, for if they do they will doubtless then face endless harassment from further suitors.

Bizarrely, firebugs have been discovered to be affected in a most peculiar manner by exposure to American newspapers. Back in the 1960s American researchers imported young firebugs from Europe for their experiments. Instead of growing into adult insects, these firebugs developed into super-sized youngsters that retained juvenile characteristics and were unable to reproduce. This never happened when the bugs were reared in Europe. The scientists eventually deduced that the cause of the problem was the paper they were using to line the rearing boxes. Bugs reared in boxes lined with American newspapers, such as
The New York Times
or
The Washington Post
, remained stuck as juveniles, while if they were reared on imported copies of
The Times
from the UK they were fine. It eventually transpired that a number of American fir-tree species used in paper manufacture contained a chemical that mimicked a hormone in firebugs and so caused their abnormal development.

Although most true bugs lead innocuous and inoffensive lives, this group includes perhaps my all-time least-favourite insect. Many years ago, when I was a poverty-stricken PhD student, I clubbed together with an old university friend and we bought a house. At the time, in 1988, house prices were rocketing, and we were worried that if we didn't get on the housing ladder soon, we'd never be able to (had we but known it, the boom was shortly to be followed by a dramatic crash, but we were young, foolish and impatient). Even with our pooled resources we couldn't afford anything in Oxford, where I was based, so instead we bought an ugly concrete ex-council house in Didcot, twenty-five kilometres to the south. Unless you are a train-spotter – for it is a major railway junction with a railway museum – Didcot is a rather dismal place, but with understandably cheap housing. We furnished the place with second-hand furniture from charity shops and rented out a room to help cover the bills.

After a few months our lodger, a cheerful, pot-smoking, long-haired biker named Mark, started complaining of a rash. He had itchy bumps in meandering lines along his arms and torso. It was summer and we initially blamed mosquitoes from the pond that I had dug in the garden, but as autumn set in and the mosquitoes should have been in decline, the rash became worse. Mark went to see a doctor, but he was unable to diagnose the cause. Mark became convinced that there was something in his room that was biting him – perhaps fleas – but we searched his mattress and could find nothing; and we had no dog or cat at the time. It was all rather unpleasant, and I started itching in sympathy. The rash got worse, and Mark took to leaping out of bed at night and searching his bedroom for the culprit (I would be woken by him crashing about, cursing), but to no avail. Eventually the poor guy moved out, and it was only then that I discovered the cause. I decided to redecorate his room, and in doing so I took down an old wooden shelf. When I unscrewed it from the wall I found dozens of empty, shed skins of some sort of insect, lodged in the narrow crack between the woodwork and the wall. They looked vaguely familiar from old photographs that I had seen as an undergraduate – photos of odd experiments on bugs performed in the 1930s by an entomologist named Vincent Wigglesworth. I started a more thorough search of the room. The bed I had bought had a sturdy old oak frame, and around the joins in the woodwork I found tiny specks of what appeared to be dried blood. There were a few narrow cracks and, peering into them, I thought I could detect movement.

By this point my suspicions were seriously aroused, and so I set about smashing the bed to pieces. When I cracked open the wooden joints, dozens of flat amber insects were revealed and began groggily scurrying about in search of somewhere to hide from the daylight. I realised they were some sort of true bug, and a few moments searching through my books identified them as bedbugs, specialist human blood-suckers. They are nocturnal, sneaking out in the small hours to suck human blood. As the blood at each bite-mark starts to coagulate, they move on a little, giving rise to the distinctive lines of bites that Mark had been suffering from. There were hundreds of them, but their ability to flatten their bodies and squeeze into the tiniest cracks had prevented us from seeing them. Somehow the bedbugs had evaded Mark's night-time searches, too. They were everywhere: in the cracks in the cupboards and even behind the skirting boards. I took all the furniture from the room outside and burned it and then had the whole house dosed in insecticide, one of the few times in my life when I have resorted to using it. Even then some bedbugs survived, and I had to have the house sprayed a second time, at twice the dose, to finish them off. It turns out that bedbugs have made quite a resurgence in the UK in recent years with the advent of central heating, which keeps them cosy and active right through the winter. They have also evolved a degree of resistance to insecticides, which explains why they weren't killed off by the first spraying.