DON’T MISS ATTENBOROUGH’S EXTRAORDINARY ANTS GAMES OF DUE TO AIR IN DECEMBER ON THRONES Wood ants live in vast super-societies led by powerful queens. Ross Piper enters their hidden world. Red wood ant (Formica rufa) workers on top of their nest synchronise the ejection of formic acid droplets to deter a potential predator. Xxxx xxxxxx Xxxx 70 BBC Wildlife December 2017 December 2017 WOOD ANTS Red wood ants are very social insects that live in colonies of up to half a million individuals, most of which are workers. Xxxxx subterranean city, a labyrinth of tunnels The loose thatch of the mound also belies the complexity employs a different strategy. Instead of turning parasite, Above left: F. rufa and chambers, home to some 300,000 Wood ant super colonies of the nest beneath, which is nothing less than a marvel she establishes her nest very close to the birth nest milks black bean occupying many separate inhabitants. At its centre, an ageing queen of arthropod architecture. The subterranean part is often with the help of a splinter group of workers. This aphids, stroking but connected nests them with its surrounded by daughters; her protectors, may have hundreds bigger than the mound you can see above ground, giving process, known as budding, is the reason why in some antennae to foragers and nursemaids. Inside and out, of queens like this one. you a good idea of the size of these structures. Shielded by populations of these ants you find nests very close draw out a drop plunderers and predators lurk. No, this the thatch is the rotting tree stump in which the nest was together forming a super-colony, while in other areas of honeydew. isn’t TV blockbuster Game of Thrones, but established, chambers for the queen, nurseries for the brood the nest mounds are more widely scattered. Above: a wood ant (F. rufa) carries something even more extraordinary. It’s the in varying stages of development – all the way from egg to These ‘budded’ colonies retain links to the ‘mother’ a cocoon over a Areality of life for some of our most fascinating insects. pupa – not to mention food stores and rubbish tips. colony, and if they are too far from food sources they do not woodland floor. Red wood ants are familiar to many of us, with six closely make any foraging trails, instead relying on food from other Why? Below: erect related species in Europe’s Formica rufa group, four of HIDDEN AWAY parts of the super-colony’s empire. Some of these non- hairs on the head which are native to Britain (though one may now be extinct Getting to grips with the nest’s structure and tracing its foraging nests may eventually form foraging trails and are and mesosoma of F. polyctena are here). Take a walk in a good bit of woodland that’s home every tunnel and chamber is next to impossible without then fully integrated into the super-colony, while others do very sparse to these ants and you will be hard-pressed to miss them. disturbing it in some way. Indeed, the challenges of working not and are abandoned. or absent. They’re often present in massive numbers and their nest out what’s going on in a nest without upsetting it is one Establishing a nest depends on the queen being able to mounds can be as much as 2m high. In Britain, some of the reason why we still have plenty to learn about wood ants. produce many daughters, which will maintain and expand best examples can be seen in the Scottish Highlands. The internal architecture of the nest and the activity therein the nest, tend to the brood, find food and repel enemies. Look closely at one of these mounds and around your feet Red wood ants is one thing, but the over-arching social structure of these This ability to produce an army of loyal daughters hinges on (F.rufa) carry a you’ll see thousands of scuttling ants. Many will have taken caterpillar back ants in the landscape is also remarkable. the mind-bending nature of reproduction in these animals. offence to your presence and be standing with jaws agape, to their nest for The story of a nest can be acted out in a number of ways, The queen ant can control the sex or spraying formic acid in your general direction, lending the colony to eat. but the beginning is always the same: young larvae in the of her offspring by using the the air the distinctive odour of these insects. Covering the darkness of a mature, healthy nest, destined to be queens, sperm she stored from her mound is a seemingly untidy thatch of pine needles and which are fed more, better quality food than the rest of the single dalliance vary sparingly. other plant material, but it is actually constructed in such a brood. Once adult, the young queens mate in the nest or If a daughter is needed, the way as to make the most of the sun’s rays to warm the nest leave it to mate nearby, either on the ground or in the air queen releases a tiny amount of as well as protecting it from rain. – a so-called nuptial flight. sperm to fertilise the egg as it is being Having mated, the queens have to establish a nest, and laid. If the queen withholds the the place they often choose is a cosy retreat in a rotting sperm, the egg is not fertilised and MANY WILL HAVE TAKEN OFFENCE tree stump. But the queens of many wood ant species are it will develop into a son. This quirk TO YOUR PRESENCE AND WILL completely incapable of doing this on their own. A young is at the root of the success of ants because it red wood ant queen, for example, becomes a parasite means that a female worker is more closely BE SPRAYING FORMIC ACID IN in the nest of a related ant species, relying on the host related to her sisters than her own offspring, workers to do all the hard work for her. so it pays for her to look after her sisters and YOUR GENERAL DIRECTION. A queen that mates underground in her birth nest the nest rather than strike out on her own. 72 BBC Wildlife December 2017 BBC Wildlife 73 GANNETS COLONIES AND SUPER COLONIES Pain-staking research involving genetics and the marking of thousands of worker ants has shown that wood ant 5 colonies can have a single queen (monogyny) or lots of 2 queens (polygyny). A colony can also inhabit a single nest mound (monodomy) or multiple, connected nest mounds (polydomy) that form by ‘budding’. In any given area, there might be a mix of these social structures. DIVE THE THATCH Enters dive from as 1This outer layer of the nest consists mostly of pine 1 low as a few metres needles arranged in a specific way to make the most of up to a height of 30m. the sun’s warming rays and to keep rain out. 6 Dive may be vertical, or as shallow as 10° NEST ENTRANCES 3 off the horizontal. 2There are several of these all over the nest mound. They can be opened or closed to maintain optimal temperature and humidity within the nest. 6 8 TREE STUMP 3The foundress of the colony often establishes the nest in an old tree stump, which might already be occupied by another ant species and so has ready-made chambers and tunnels. As this stump decays, it helps to 7 keep the nest mound warm. With a nest well and truly established, this sisterhood Above: ants from 6 begins to exert a powerful influence on its habitat. The the Formica QUEEN CHAMBER rufa group are driving preoccupation of the multitude of ant workers In the deepest part of the nest resides the queen, protected by law 4 9 is sourcing food for themselves and their nest-mates, in many European attended by workers and laying a stream of eggs. Deep including the brood, which are particularly ravenous. If countries. The down in the nest, she can live as long as 15–20 years. you watch a nest – or a foraging trail leading to it – for any insects play 6 length of time, you’ll see bits and pieces of various insects important HOT ROOM ecological roles. and spiders that have been butchered and are being 5Eggs from the queen are taken by workers to the top transported back to the nest to be fed to the brood. of the nest mound, where temperatures can be higher, to Any arthropods are fair game. Caterpillars, beetles or hasten their development. spiders that find themselves on the wrong side of a foraging party will be quickly subdued and dismembered. Although BROOD CHAMBER these ants are very capable predators and scavengers, their 6Mature eggs are taken from the hot room to brood most important food source, making up 90 per cent of their chambers deeper in the nest, where their every need is diet, is the sweet liquid – honeydew – that oozes from the attended to by an army of nurse-maids – their older sisters. 7 back-ends of aphids high in the trees that surround the nest. 4 REFUSE CHAMBER SUPPLY AND DEMAND 7Ants are scrupulously tidy. They have to be, because An ant delicately strokes an aphid with its antennae to conditions in the nest are perfect for harmful fungi and elicit a droplet of honeydew, which it greedily consumes – a bacteria.