The worker ant is usually only 5mm long whereas the queen is around 15mm long. The most common ants in Britain are the black ants and the garden ants. The worker ants are usually dark brown and the queen who will rarely be seen outside the nest is a lighter shade in colour.
The queen will make the nest, usually outside beneath patios and paving or in grass/soil areas. The nests can also be found inside houses, in the foundations or walls. The worker ants will forage for food and once one has found a good source there will soon be others.
Although ants are not a health risk to humans they are a nuisance and if the ants have established a colony in your home or garden it may be necessary to proceed to M Pest Control.