Common black ant
Garden Ant Lasius Niger
Key Features:
As with all social insects, there are a number of different castes comprising a complicated community within the ants’ nest. The workers are the most common caste and the ones that are most likely to be seen by the pest controller. Males and queens are produced at certain times of the year and these are the winged individuals, the so-called flying ants, which are common on thundery days in summer. The workers of L. niger are about 2-5mm in length, almost exclusively black or black/brown in colour although the bases of the antennae, the tarsi, and the leg joints have a yellowish colour. The presumptive queens and males are larger in body size, 6.6-10mm and 3.5-4.7mm respectively, again predominantly black but on emergence from the nest they have wings. The wings are lost by the female once mating has taken place and the males die shortly after mating.
Biology:
Ant societies are centred upon a complex nest that arises after the mated queen has established a small starter nest beneath the soil. The queen rears the first brood of larvae within the nest, feeding them on saliva. These larvae mature and then pupate to form the first cohort of worker ants. While she is rearing the first batch of larvae, the queen uses the reserves from her flight muscles etc as food. The colony then grows rapidly with the queen continuing to lay eggs which are tended and fed by the workers. The ants feed on nectar, seeds and small insects, aphid and coccid honeydew, etc and the nests can remain viable for many years. As mentioned above there are periods during the late summer when the sexual forms are formed, often in substantial swarms. Climatic conditions affect this since the males and females exploit the thermal currents to rise and mate in mid-air. Typically mating flights occur in August, following stormy weather. Very few of these fertilised queens survive to set up colonies.
Distribution:
Eurasia, northern Africa, North America, and carried to southern Africa.
Significance:
The only indigenous British species that commonly enters houses. L. niger is the most common ant in Britain. Nests are typically found in soil but may be under paving stones and concrete. When ants have nested indoors, infestations may cause problems at any time of the year. In such circumstances, their nests are usually found in the insulation layer below a property.
The garden ant can pose a real problem as a nuisance pest. During foraging, workers may be found in domestic and industrial premises searching for sugary food sources. The mating swarms can also be a
short-term nuisance.
Control:
Accessibility to the nests may be restricted and yet this is the key to gaining control of the infestation. Following trails of worker ants back to the nest should help to locate their position. Gel baits are now available for black garden ants. These rely on the worker ants picking up the bait and taking it back to the next to feed the queen. Therefore baits should not be used in conjunction with residual sprays. Baits are best placed where the ants are foraging-in and around nest entrances, adjacent to ant trails and in cracks and crevices between paving slabs, concrete foundations etc. Alternatively, residual insecticidal treatments on a property to prevent foraging workers gaining access. Good hygiene so as to reduce attraction for ants can be applied in or around the nest. Barriers of insecticide may also be utilised around strategic points on a property to prevent foraging workers gaining access. Good hygiene so as to reduce attraction for ants is also important.