Pest control: ants

The common black garden ant (Lasius niger) is not considered a risk to public health, however from time to time they  can  become a nuisance. They are dark brown or black in colour and 3-5 mm in length. They generally live outside, but will often invade buildings in search of food and this is when they can be a nuisance. Ants are social creatures and live in colonies which contain worker ants (infertile females), males, queens and grubs (the larval stage). Although omnivorous, in common with other ant species, the black ant has a liking for sweet foods. Nesting sites are frequently found around foundations, under paving slabs, the edge of flower beds and lawns. Sandy and clay soils are preferred.

Although black ants are not inherently dirty insects and there are no health risks associated with them, because they travel considerable distances foraging for food they may walk over unclean surfaces and could theoretically contaminate open foodstuffs. When a foraging worker ant locates a food source it will very quickly communicate its find to other workers and in a very short time your kitchen work surfaces or food waste bin will be overrun with ants. Although there are no real heath risks associated with black ants, because it is unpleasant to have such large numbers of insects invade your home, it is best to not encourage them by leaving sweet and sugary foodstuffs uncovered and food waste or spillages uncleared. Large swarms of flying ants appear each year in early summer. These are winged males and females that take flight to mate on the wing. After mating the male dies and the female bites off her wings, and lays dormant in the soil over winter. The following spring these young queens lay eggs which hatch into white larvae. These are fed by the queen until they are ready to pupate. Worker ants emerge from these pupae and it then becomes their job to feed new lavae and the queen ant. In favourable conditions, nests can often survive for a few years.


The legal position

There is no legal requirement for the Council to provide a ant treatment service.


The service provided

In most cases it is best if you can deal with the problem yourself, however the Council does provide a black ant treatment service for both Domestic and Commercial properties. The Council is not legally obliged to provide this service and therefore has to make a charge to its customers.

The treatment consists of spraying an insecticide onto the nest. This treatment can obviously only be carried out when the location of the nest is known. The insecticide works rapidly and kills most insects on contact. There are however rare occasions when it does not completely work and should the nest still be active 4 weeks after the final treatment please let the Council know and re-treatment will be arranged at no extra cost.


Safety Information

The insecticides used by the Council are the safest available and do not pose any risk to people or pets with the exception of fish which have similar body structures to insects and so can be affected if they come into contact with the insecticide. You will however be provided with an information sheet on the insecticide used.


What you can do

Control measures should only be necessary where ants are invading a property.  Ants will generally only  come into your home if there is a food source readily available, especially if it is a sweet or sugary type. To prevent ant invasion, good hygiene is essential.


  • Make sure all food waste and spillages are cleaned up immediately
  • Keep foods in sealed containers, especially foods like jam, honey and sugar
  • Ensure that any fruit on display is not over-ripe and weeping
  • Avoid leaving pet food out for long periods
  • Ensure that rubbish bins are emptied regularly and washed out of any food residue
  • Make sure all cracks, gaps and crevices in the walls and floors of your property are properly filled and sealed against entry


Should all else fail there are many brands of household poisons and insecticides that are available from hardware stores, garden centres and supermarkets, that are suitable for home treatment of ants. However if you choose to use these materials, you must follow the manufacturers instructions to ensure both the effectiveness of the product and its safe use.

Many people use the simple but effective method of scalding the nest with boiling water. For health and safety reasons, Redbridge Council does not recommend this method of treatment.


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