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FACT SHEET - Ants (Lasius niger)

Black Ants (also known as Garden Ants) are very common and are mostly harmless, although they can be a nuisance if they come into houses. Ants are useful garden insects, collecting nectar and seeds from flowers and also small dead insects, all of which are taken back to the nest to feed the larvae.

Life cycle

The life cycle starts with a fertile queen digging into the ground to make a small cell in which she lays eggs. These hatch in about 3-4 weeks into larvae. Within a further 5 weeks these larvae turn into adult ants. These ants, all sterile female workers now forage for food and tend the queen ant who continues to lay eggs thus enlarging the nest. In late summer, male ants and large fertile female ants are produced. These ants have wings and can fly. They will leave the nest, sometimes in large enough numbers to make a noticeable swarm and will mate while flying. All the male ants and many of the female queens will die fairly quickly, but the queens which survive will set up new nests. The nest is most likely to be outside the house, particularly in sandy soil, or in the sand bed laid beneath garden paving slabs or around the foundations of houses. Ants move indoors to feed or emerge through cracks at skirting board or ground level.


Ants are attracted to sweet foods - they will collect sugary secretions from greenfly and will be attracted to any sweet substances in a house.

Ants that have been successful at finding food, particularly sweet foods, can communicate this to other ants, and if the source of food is in a kitchen this will result in large numbers of ants forming a trail to the food. Although unpleasant, black ants do not transmit diseases.


If houses are infested by ants there are three steps to controlling the infestation:

1. Any obvious defects in the building should be repaired with mastic or cement mortar - cracks and gaps around doors, steps, patio windows etc. However, given the tiny size of ants, and their determination to reach sweet foods, this may not be sufficient to stop them.

2. Any sources of sweet food in the kitchen should be covered or cleaned away - sugar bowls and jam dishes should be emptied and loose food stored in plastic or glass containers with tight fitting lids. However, even a small drop of sugary lemonade spilled down the back of an inaccessible cupboard may be attractive and impossible to find and remove.

3. A pesticide spray treatment can be very effective, particularly if it has a residual effect which will last for a few weeks. Professional pest control operators have access to effective insecticides and the professional sprayers and dust guns to apply them. Although there are many aerosol sprays and gels available from DIY shops, these may not have the penetration or residual effect that can be obtained with professional sprayers.

Please note SDK Environmental only provides an ant control service for infestations indoors. We do not conduct outdoor treatments.

For any treatment to be effective there are certain actions you the householder needs to take before and after any treatment provided, all responsible pest control companies will advise you what you must do.

SDK (Environmental) Ltd trading as Dial A Pest, Acorn House, Aspen Way TQ4 7QR.
Full terms & conditions can be found at www.dialapest.co.uk