Lasius niger


My favourite species of ant, and the most commonly seen species found in the UK, Lasius niger are a fascinating ant, and make ideal ants to keep in captivity for the beginner.

Identifying Lasius niger

Lasius niger is an easily recognised species of ant in the UK.  These ants are medium-sized, ranging in size from 2.5 mm to 5 mm.  The smaller specimens tend to belong to first and second-generation workers from new colonies.  The diminutive size of these early worker ants is due to the lack of food resources available to them during the first, and early, stages of colony founding.  As the colony grows, and more food comes in from the increasing numbers of workers foraging, so the larvae have a better food supply.  As a result, the adult ants that developed from the larvae are bigger.

Lasius niger appears black to the naked eye, though they do have a hint of brown on the mesosoma (thorax – the middle section of the ant’s body).   This species of ant can be confused with other Lasius species when looked at with the naked eye.  Examples include Lasius platythorax, L. cinnerus, and L. alienus.  However, with a microscope, a more definite identification can be made.

Lasius niger
Lasius niger

Identification Key

When looked at through a microscope short, upright hairs on the scape of the antennae, and the tibia of the leg can be seen.   The scape is the first part of the antenna, from the attachment on the head to the “elbow” joint.  The tibia is the lower leg of the ant.  Further hairs are found on the body, including the clypeus, head, thorax, and abdomen.

Eyes and eyesight

Most ants have compound eyes made up of ommatidia (the individual lenses).  The number of ommatidia per eye is dependent on the species.  Lasius niger has 120 such lenses per eye.  Though ants generally do not have good eyesight, that that does depends on species. Some species of ant are totally blind, whereas others are rather keen eyesight.  Lasius niger fall into the more common group where sight in concerned. They can make out certain objects, which helps them to navigate using visual clues.  However, their eyesight is quite poor.

Distribution and habitat of Lasius niger

Lasius niger is found all over the UK (though are sparser in the north of Scotland). Europe and Scandinavia, except for the most northern parts of Sweden, Norway, and Finland also have them.  However, although they are found in the Mediterranean areas, they are not so common there.  Rather, Lasius grandis and L. cinereus are more common in those parts.

They are found nesting in a wide variety of places, more commonly in parklands, gardens, and other cultivated areas, where the soil is easier to construct their nests.   They do live in grasslands such as meadows but appear to only do so when they can excavate their nest under a stone. 

Lasius niger is not usually found at altitudes above 1500m.

Diet

Lasius niger forages both below and above ground. Because of this their diet is more extensive when compared to, say, Lasius flavus.  This latter ant conducts all its foraging below ground.  The staple diet of Lasius niger includes many insects and arthropods. This includes, the larvae of such, and caterpillars, earwigs, woodlice, flies, and other ants.   Lasius niger also thrives on the honeydew provided to them by various species of aphid.  These ants also prize some nectars.

Foraging

Lasius niger forages individually and collectively.  A worker will carry or drag the prey back to their nest alone.  However, sometimes the prey may be too large for one ant to carry. Or the food may not be able to be carried because of its nature, such as a liquids. In this case the worker will recruit help from its nest-mates using pheromones/chemical trails.

Navigation

Like many species of ant, Lasius niger uses various methods of navigation.  This can be as simple as the recognition of visual landmark clues.  Pheromone/chemical trails, or the position of the sun in the sky, as well as the pattern of light and shadow on the ground, also are important determinants.  The latter would require the ability to compensate for the movement of the sun across the sky, and the associated changes in the light and shadows.  Experimentation has shown that the ants do, indeed, have this ability.  Likewise, ants, such as Lasius niger, can detect the patterns of ultra-violet light in the sky.  This is something we humans are unable to detect with our eyes.

Nests of Lasius niger

Lasius niger like to build their nests in damp soil.They often start by excavating soil from beneath a hard object, such as a stone, or the edge of a pavement.  However, it is known for Lasius niger to invade the nests of other species of ant. Lasius flavus, which is a much more skilful nest-builder than Lasius niger, is one example.  Once they have defeated the resident ants, Lasius niger will claim the nest as their own and move in.  Lasius niger nests can be extensive, with up to 10,000, even 15,000 ants living in one nest.

In gardens, Lasius niger seem to prefer to nest in soil beds, against or under objects such as pavement edges or walls, rather than directly in the grass.   Newly mated queens of Lasius niger appear to avoid lawns when looking for a new nesting site.  This may be because lawns often are home to Lasius flavus, or because soil beds are far easier for the queen to excavate a nest in, rather than the denser soil of grassy beds.

Queens

The number of egg-laying queens present within an ant nest does vary between species.  Formica rufa, for example, can have hundreds of parent queens.  However, Lasius niger is monogyne. This means they will only tolerate one egg-laying queen being present in any one colony.  It is quite common for more than one newly mated Lasius niger queen to come together to initially found a new nest.  However, once the first generation of workers is born, all but one of the queens, usually the most prolific at egg-laying, are killed.  Lasius niger mating flights usually occur late June to August, in the afternoons, particularly after a short shower of rain on an otherwise hot, windless day.

Defence

Lasius niger are very capable ants when they must defend themselves.  They will aggressively defend their nests, brood, and queen.  They are strong and can spray formic acid, though not to the impressive range of the Formica rufa red wood ants.  Though their bites are not often felt by humans, I can say from experience, that occasionally a Lasius niger worker will bite sensitive areas that can certainly be felt.  I once disturbed a nest of Lasius niger, and one worker latched onto the skin between two of my fingers and gave me a good hard bite.  Though not particularly painful, I most certainly became quickly aware of this ant as it tenaciously attacked me.

Aggression

Lasius niger are also aggressive towards other ants. This includes queens of their own species that do not belong to their colony.  In fact, Lasius tend to kill more queens of its own species than of any other in the UK.  Lasius niger do not like competition in their territory and will quickly dispatch any foreign ant, queen, or worker, who strays into their territory.  Killed queens provide the larvae with a good nutritious meal too. I have seen a Lasius niger colony in my own back garden absolutely decimate a nearby Myrmica rubra colony.  Though the workers of Myrmica rubra are larger and stronger than those of Lasius niger, the latter have far more populous colonies. As a result, they were able to overwhelm the rubra by sheer force of numbers.

Lasius niger vigorously defend their territory.  The size of the territory depends on several factors, such as colony size and food supplies in the area. Where the territory of two ant colonies meet, fighting may not necessarily ensue.  Ants are aware of where their own territory ends and that of a neighbouring colony begins. Where skirmishes happen, for example, when a food source has been found along the border of two colonies, this will often end in a show of strength rather than a fight to the death.  Mock battles, as it were, take place where the victor pins down the loser.  However, if food is scarce within the territory of one colony, then real fights may occur.

Keeping Lasius niger in captivity

When asked by UK residents, which is the best ant for a beginner to keep, I always, without hesitation, recommend Lasius niger.  These ants are easy to keep in ant farms, and remain highly active, so long as there is a queen and brood present.  No specialist nesting materials is required. Lasius niger are happiest when living in soil.  Lasius niger are easy to feed because they eat a wide variety of foods, including many species of insects, including flies, crickets, beetles, arthropods such as woodlice. The ants will also eat the larvae of many insects.  Lasius niger queens are prolific egg-layers once the colony is established, usually after its first or second year.  Again, the larger a colony, the more brood present, the more active these ants will be.

I keep ants, including Lasius niger and have done so for many years.  Lasius niger will always be my favourite species.

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My Ant Farms (Oct 19)
My current ant farms as of October 2019