Black Garden Ants nest mainly in dry soil and humus. Although their nests are most often noticed in gardens – in flower beds, lawns, and under paving stones – they are also common in dry grasslands and heaths.

From their nests, they forage widely for food along scent-marked trails across soil and ground vegetation, and – most noticeably – across paved surfaces and into houses, where they are attracted to sugar and crumbs.

Outside human habitation, they feed on many things: small live insects, dead insects, nectar, seeds, etc. They also feed on the sugary secretions produced by aphids, some other sap-feeding insects and certain caterpillars, and often tend them to protect the source of this food from predators.

The ant builds its nest in soil, under stones or in tree stumps and it frequently nests underneath paving stones. It may sometimes occupy the nests of other species of ants, colonies number around 5,000 individuals. Small black ants 'milk' aphids, collecting drops of sweet honeydew exuded by the aphids. An extensive range of food is eaten, including seeds, flies, flower nectar and other small insects, which are killed and taken back to the nest Aphids may even be taken into the nest. Winged reproductive males and females engage in a mass mating flight in hot, moist weather throughout July and August. Males die after mating, and females set up new colonies. Queens mate only once, storing adequate sperm inside her body to last her lifetime. The mating flight makes sure that the species disperses; also increasing the chance that males and females from different nests will mate, avoiding inbreeding, the winged reproductive adults of different colonies in one area fly at the same time. After finding a suitable site, the Queen begins to produce eggs. The resulting workers are non reproductive females, who take over the care of the colony. After hatching, the larvae at the beginning feed on un-hatched eggs, they are then fed with regurgitated fluid.

Foraging worker ants cause a nuisance as they travel widely in search of food, following well-defined trails and clustering around the food source. Primarily a nuisance pest, the Black Ant does not pose a significant threat to public health, although they are obviously an unpleasant sight and may damage food used for human consumption.

A careful inspection is necessary before any treatment is started. Ask the client if they have noticed where the ants seem to be coming from, look for all entry points in cracks and crevices in or around the kitchen, bathroom and laundry areas. Initially treat all cracks and crevices and entry points, Gel baits are available for black ants. These rely on the worker ants picking up the bait and carrying it back to the nest and feeding the Queen, place baits where the ants are foraging. Outside try to track the ants back to their nests and flood with a residual insecticide. Spray paved areas lightly, lift up and treat under pot plants. Be cautious with cracks in concrete and under paths. Inform the client to move rubbish bins and pet bowls away from the house.

Ghost Ants

The ghost ant is sometimes known as the black-headed ant. This ant is very small at about 1.5mm in length, with a dark head and thorax. The pale coloured, almost translucent abdomen and legs, in addition to its tiny size, gives the ghost ant its name.

Although having only arrived in the UK in recent years, and still relatively rare, the ghost ant is spreading quickly, particularly in large housing developments. The ghost ant colony can be moderate to large in size, containing thousands of workers and multiple queens. The colony is usually divided into sub-colonies, this is because the areas where ghost ants prefer to build nests are usually too small to house their huge numbers. Different ghost ant colonies do not attack one another and will even integrate with their neighbouring ghost ants. Ghost ants have a preference for sweet foodstuffs. Outdoors they feed on the honeydew from aphids and mealy bugs, indoors they will seek out sugar, sweets, syrup, honey and jam. The biology is similar to the pharoah ant.

Spraying with a residual insecticide where trails are seen is more likely to achieve results than with pharaoh ants, however, because of their small size and ability to form new nests, re-infestations often occur in other parts of the building. Combination treatments with gels and slow acting liquid baits are usually advised.

Pharaoh's Ants

The pharaoh's ant is a small ant of tropical origin. The workers are only 2mm long, the queen 5mm long and both are yellow in colour. The ant has a characteristic double segmented waist and a darkened tip to the abdomen.

In temperate climates it is an indoor species, associated particularly with large facilities such as hospitals, prisons and blocks of flats. Unlike some other ant species, the queen may be replaced by other queens. This is an important feature to bear in mind during control, as new queens can be produced when needed resulting in colonies which are able to split. There can be many queens within a single colony. Pharaoh's ants can reproduce in two ways, firstly when a colony is big enough it produces males that fly from the nest and find another colony where they will mate. Secondly by budding, where a scout finds a new suitable nest site and some workers and a queen migrate to it to form a new nest.

A thorough survey by professional personnel is highly recommended. Pharaoh's ants are most often found in areas near a source of moisture such as a kitchen or bathroom. The use of conventional residual treatments is generally not effective as they may cause the nest to fragment. Baiting may be effective if the active ingredient is slow acting. Good results have been shown by using juvenile hormone based treatments. The treatment consists of applying bait to areas frequented by the ants, which works by stopping the ants breeding and so they naturally die off. You will usually notice a reduction in the number of ants within 28 days, but it may take longer to kill off all the ants. Although modern treatments are very effective, there are rare occasions when it does not completely work.