A Buzz in the Meadow

by Dave Goulson

  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.

  I later looked through my undergrad notes to remind myself of the lectures I had received on Wigglesworth’s experiments. Sir Vincent Brian Wigglesworth, to give him his full title, was a great pioneer of studies of insect physiology and the hormonal control of moulting and growth; he is one of very few entomologists ever to receive a knighthood. Wigglesworth served in the army during the First World War, before studying natural sciences at Cambridge, where he eventually became a lecturer and professor. Quite early in his career he discovered several of the major hormones found in insects, including the juvenile hormone whose analogues are found in paper made from North American trees. His discoveries were underpinned by macabre experiments that he conducted on bedbugs and their relatives.

  To demonstrate the presence of a hormone in the body fluids of insects that controls moulting, he decapitated bugs and joined their headless corpses with short lengths of glass ‘microcapillary’ tube – the same type of fine tube that I commonly use to extract nectar from flowers. Once joined in this way, the pair of bugs are strongly reminiscent of a mating couple, except that instead of being tail to tail, they are joined neck to neck. The tubing connects their body fluids, so that any compounds within can flow or diffuse from one body to the other. Although the bugs might reasonably be described as dead at this point, for they have no head or central nervous system (brain), nonetheless they continue to function for many days. As you might imagine, they don’t do a great deal – without a head, neither body will decide to go for a walk, and they obviously can’t feed. However, their tissues are still alive, they continue to respire and their bodies can moult, shedding their skin and thereby producing the cast skins that I had discovered in Mark’s room. Wigglesworth found not only that a decapitated bug could moult, but that if he decapitated a bug that was close to moulting and joined it up with a slightly smaller bug that was nowhere near moulting, then both would moult together. Something was being transferred from the larger to the smaller body, causing it to moult prematurely.

  Wigglesworth focused particularly on bedbugs and their relatives, the kissing bugs, and tried joining the different species together. He found that the hormone that controlled moulting was common to both, so that conjoined corpses of the different species also moulted in synchrony. Similar hormones are now known to be found in all insects, although it was many more years before their chemical structures were elucidated.

  One of the few positive things to be said for bedbugs is that they do not spread disease. Many biting insects do; most famously, mosquitoes spread malaria and a host of other life-threatening diseases, such as dengue fever and yellow fever. Aphids offer a similar service for plant viruses – between the many types of aphid they spread at least 150 different viruses, many of them very harmful to crops, including such colourfully named diseases as beet mosaic, cherry ringspot, onion yellow dwarf and tomato-spotted wilt. One of the relatively few examples of a true bug that spreads human disease is the kissing bug of South America, the insect that Wigglesworth had imported to conduct his experiments. These large brown insects, about two and a half centimetres long, live in crevices is rural houses and huts. Like bedbugs, they sneak out at night to feed on sleeping humans, where they prefer to feed on the soft, delicate skin of the lips, which is easiest to penetrate. It is from this sinister habit that they get their name. While feeding they often defecate, and inevitably some of their faeces fall into the mouth of their unfortunate sleeping host. Even when the kissing bugs do not feed on the lips, they can infect their unfortunate host, for their bite-marks cause itchy lumps, and the scratching they elicit can lead to the insect’s faeces penetrating the wound. The faeces contain virulent spores of Trypanosoma cruzi, a single-celled protozoan related to the parasite that causes sleeping sickness in Africa. The South American parasite causes Chagas’ disease, an unpleasant chronic illness that is thought currently to infect about eleven million people in Central and South America. Many people suffer no symptoms, but about one-third develop inflammation of the heart and sometimes also the gut, with the heart damage eventually causing death. It seems that Charles Darwin was the unlucky recipient of a kiss from one of these bugs when visiting South America on a stop-off from The Beagle’s voyage. In his diaries he describes being bitten while exploring near Mendoza in Argentina:

  At night I experienced an attack, & it deserves no less a name, of the Benchuca, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over ones body; before sucking they are quite thin, but afterwards round & bloated with blood, & in this state they are easily squashed.

  For much of his later life he suffered from a range of symptoms that were never diagnosed, but which approximate to those caused by Chagas’ disease – the disease was discovered by Carlos Chagas some thirty years after Darwin’s death. Some have suggested that Darwin was simply a chronic hypochondriac, the condition perhaps brought on by worry at the prospect of publishing his theory of evolution by natural selection, but it may be that the poor chap was genuinely suffering from a life-threatening illness.1 There have been moves to test Darwin’s remains for DNA fragments of the parasite, but the authorities of Westminster Abbey, where he lies entombed, have so far refused permission.

  If bedbugs and kissing bugs sound as if they are best given a wide berth, their cousins the African bat bugs are arguably more gruesome still. These creatures closely resemble bedbugs, but inhabit caves in East Africa, where they feast upon the blood of bats, being active in the daytime when the bats are asleep. In a wonderful irony, they have South American cousins that suck the blood of vampire bats. The mating habits of the African bat bug are perhaps amongst the most barbaric yet discovered in the animal kingdom, and should perhaps cause human females to reflect that, no matter how clumsy their lover, matters could be much worse. The penis of the African bat bug is not dissimilar to its mouthparts – a sharp, pointed tube. Instead of inserting this into the genital opening of the female in the conventional manner, the male bat bug simply grabs the female and stabs his penis through her body wall, injecting his sperm directly into her body cavity, from where it swims to fertilise her eggs. Females are forced to mate many times in their lives, and so can accumulate considerable tissue damage from the multiple stabbings. To make matters worse the male’s penis is far from clean – personal hygiene not being a high priority in the bat bug – and so it introduces bacteria into her body, which can lead to infection and death.

  In an attempt to combat this, female bat bugs have evolved a fake ‘genital opening’, a funnel on their back that tries to guide the sharp penis of the male into a cluster of immune cells, which mop up the bacteria. Females still sometimes get stabbed elsewhere, but the damage is reduced.

  This sordid story has a further twist. As in many animals, the males are not terribly discriminating in their courtship. They frequently grab and stab other males, causing them considerable damage in the process. As a result, some males have also evolved a fake genital opening to try and minimise the damage, but this in turn makes them look a little more like females and so increases the frequency with which other males try to mate with them. It seems there is no escape for either male
or female bat bugs from the damaging sexual depredations of the males of the species.

  In marked contrast to the degenerate bat bugs, some true bugs eschew sex altogether for much of the year. Some of the flowers in the meadow – notably including white campions, creeping thistles and meadow vetchling – are commonly attacked by blackfly, sap-sucking aphids. In chapter twelve we will look at why most animals have both males and females and reproduce sexually. Aphids are one of the interesting exceptions, at least during the summer months. The clusters of blackfly on thistles are predominantly wingless females. They plug themselves into the phloem, the network of tubes that transports sugar-rich sap around the plant, and then rarely move again unless they are attacked or the plant dies. They squirt out youngsters at a prodigious pace (up to twelve per day) and these are genetically identical copies of themselves – a process known as parthenogenesis. If sheep could do this, it would have saved scientists the enormous effort and expense that went into producing Dolly (the first artificially cloned mammal). The offspring walk a few millimetres from their mum, plug themselves in and repeat the process. In some aphid species, offspring have their own young already developing inside them as they are born, recalling Russian nesting dolls that are packed one inside the other. Hence one aphid quickly becomes thousands, all identical females descended from a single individual. They sacrifice the advantages associated with sexual reproduction – the mixing of genes – for extremely rapid reproduction.

  Only when summer ends and they find themselves under heavy attack from predators, or the plant starts to weaken under the load of aphids, do they change strategy. When this happens, they start to produce both males and females; and what is more, these offspring have wings. They fly away, mate (and so jumble up their genes once more) and start fresh colonies. In autumn they tend to set up their new colonies on woody plants in the hedgerows, where they can survive the winter in relative safety.