Latin: Lasius niger
The common ant in the garden, in courtyards and roads is the black garden ant, which in Latin is called Lasius niger. In fact, it is this species of ant that one will encounter in houses.
Appearance
Due to the name, one is tempted to believe that the black garden ant is just black, they are brown. The working ants are 3.5 and 5 mm long. On the outer antennae there are small hairs.
Biology and behavior
Black garden ants live in gigantic communities. Those communities usually house 5,000-10,000 members.
The members are of various individuals, from unwinged workers and winged males to queens who are winged females.
It is the wingless workers who manage the practical work in and around the anthill. These are female ants with undeveloped ovaries. The worker ants search far and wide for food. If a worker finds something good and edible, it passes it on to the other mates by creating a scent track towards the food item, while the worker ant claps other ants with its antennae. The worker feeds the others with the food found, and now a caravan of ants will find their way to the site.
The predominant food for the black garden ants is sweet liquids, which is the excrement from aphids. To a certain extent, they get nutrition by overpower and eat various small animals.
They build the anthill in the ground, preferably under tiles or stones, but they can live in moisture damaged wood or rotten tree stumps. Once a year during the summer, a swarm of winged ants will emerge from the anthill, where they will mate with other swarming ants from a different habitat. The surviving females subsequently build new communities, where they will spend the rest of their lives laying new eggs.
Damage
Houses that are built directly on the ground are often visited by the garden ant. The ants settle directly under the concrete floor, where they do penetrate through cracks, like foot panels, and pipe penetrations. They can also settle between the insulation material of the wooden and concrete floor, this will however, damage the wood floor.
The first signs of ants inside the house are small piles of gravel or sand that appears at panels. Such piles are the landfill of the anthill, containing the remains of dead ants, and empty pupae.
In Denmark it is common to have garden ants visit houses, they rarely destroy anything. The black garden ants do not have the ability to undermine the house. When they do build their nest in or near houses, the wood has been damaged in advance by moisture. However, damage can occur in the woodwork if the anthill materials touch wood.
It is important to know that there are other species that can damage the wood, and they do look like the black garden ant.
Prevention and control
Effectively control of the black garden ant is finding and destroy the anthill. This can be difficult, as they often live underneath the house, where it is not possible to destroy the place where the pupae, larvae, eggs, and the queen are. When using insecticide, make sure to use the proper agent, that is approved for ant control. Make sure to follow the instruction on the label.
If the ant nest is located right by the plinth or doorstep of the house, you may risk the black garden ants indoors. In such cases, the anthill is controlled with ant powder or irrigation.
If you do find the black garden ant outdoors, you should consider to what extend you want to sabotage it. In the right conditions, one can use boiling eater without ant poison.
Indoor control requires the use of aerosols with pyrethrin, spray, ant powder or poisoned bait. If the ants are on kitchen shelves then you should only use harmless means.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)