Ants are among the most abundant organisms on Earth, with some estimates suggesting that there are over 10 quadrillion alive at any one time, mainly in tropical rain forests. There are around 50 ant species in the UK, and some experts suggest that this number will increase as our climate becomes drier as a result of global warming. Gardens are home to several species of ant, many of which 'farm' aphids for their sweet honeydew. In return, they protect the aphid colonies from attack by natural enemies. They will carry individuals to fresh host plants so that new colonies can be founded. Have a look at any large aphid colony and you are likely to be able to see this amazing interaction at work. Some ant species are among a critically important group of organisms ecologists have termed 'ecosystem engineers', as they can have a profound effect on their environment. However, common garden ants are not in this league, although they can cause some minor disturbance around plants as they dig their nests.
Ants have complex social structures, with a queen, males and a large number of workers. The queen may live for up to 15 years.
Red wood ants, Formica rufa, are renowned for their defensive behaviour, attacking potential threats with a combination of biting and squirting formic acid from a specialised gland in their abdomen.
Several bird species will groom by sitting on ant nests (especially wood ants), and allowing the ants to clamber over them. The ants' formic acid may kill some of the birds' lice.