Species of the day: Black Garden Ant

By James Duncan

Learning & Engagement Officer

The Black Garden Ant (Lasius niger), also known as the Common Black Ant is perhaps one of our most familiar garden insects. So incredibly familiar that it's almost certainly thoroughly overlooked. It's likely the cosmopolitan Black Ants go about their daily business with us barely giving them a second thought, even though they're the most species-rich social insects on Earth, inhabiting every single major landmass with the exception of Antarctica. Ants are most closely related to both the Bees and Wasps and all are contained together within the huge insect Order Hymenoptera. Ants have an ability to thrive in almost any ecosystem and there's little doubt they comprise a significant percentage of the planet's terrestrial biomass. The fossil record suggests that ant lineage dates back to the Cretaceous period, diversifying from a Vespoid Wasp ancestor in line with the origin of flowering plants. The complexity of ant society has long been studied, with their communication, division of work and problem solving ability showing remarkable similarities to human society. Their incredible social abilities in both modifying habitats and exploiting resources have no doubt fuelled their success. As a whole, they tend to prefer warmer environments and of the twenty-two thousand currently described species, around sixty are found in Britain, including those both native and introduced. 

The number of ant species in any area is typically dictated by the maximum soil temperature, the higher the better. With our temperate climate the majority of British ant species are, as a result, concentrated in the south and are surprisingly specialised in their habitat requirements. The Black Garden Ant is one of the few exceptions to this specificity. It often arrises and proliferates owing directly to human activity and disturbance and may be found almost everywhere - it's certainly one of the commonest in Europe. There are typically a couple of ways in which we come into contact with this ant. The first usually arises through their habit of 'home invasion' as they search for a sugary food-source, amongst a surprisingly varied diet. The second is during mating season, when nuptial flights are performed by the winged adults. These will normally occur on hot and humid days during July and August, sometimes occurring simultaneously, though they are dependent on localised weather. The flying ants, known as 'alates' comprise sexually mature 'virgin queens' known as 'gynes' and super short-lived males whose only role is to mate. The swarms produced by flying ants can reach dizzying proportions, the strategy serving as an effective method in maximising mating encounters. The volume of ants also ensures greater safety through sheer numbers, though vast quantities are still lost to feasting birds. Once mated, the males will quickly perish whilst the queens will chew their wings off, absorb their now unnecessary wing muscles for nutrition, and disperse to hunt for a new nest site.

Black Garden Ants are polymorphic and exist in distinct castes within the colony - worker, queen and male. The workers are all females, sisters in fact, and they're all sterile. They'll undertake a multitude of roles depending on their age; some within the colony tending to the queen, eggs and larvae; some outside the colony both hunting and foraging. They're the tiny ants with which we're most familiar, usually 3-5mm long and perhaps numbering 15,000 in a decent sized colony. It's only during summer that the fertile members of the caste are laid, the females of which will strike out to begin new colonies as queens. The unfortunate males are typically around 5-7mm, though usually smaller than the queens who, quite incredibly, may reach ten to twenty years old, even more in some cases. The furious mating undertaken during nuptial flights will enable a queen to store enough sperm to lay thousands upon thousands of fertilised eggs, for the remainder of her lifetime. Ants are renowned for coevolution with other species, forming a whole host of symbiotic relationships. Black Garden Ants are no different and regularly employ a mutualistic relationship with aphids who they 'farm' for honeydew, a favourite food of theirs. The aphids gain protection in return and may be tended to in a very similar vein to that of humans and cattle. The Silver-studded Blue butterfly also has a mutualistic relationship - its larvae are nurtured by this ant (amongst others) and release a sweet sugary secretion in return. Black Garden Ants are fantastic soil engineers, mixing it up to aid fertility, though their superb ability to adapt to urban surroundings may be their most impressive trait. 

Black Garden Ants © James Duncan