Collins New Naturalist Library. M. Brian V.

and ladybirds. Many aphids and coccids attended by ants have shelters of soil and vegetable particles built around them. These must help the ant to keep off dangerous animals as well as providing a more equable microclimate, not only for the benefit of the bugs but also for the ants which are reluctant to forage in wet and windy weather. Formica rufa cannot construct aerial chambers and loses a lot of aphids during storms but it does excavate underground and some of its aerial aphids may be found there.

      Many underground aphids have evolved high degrees of dependence on ants, so much so that they are never found alone. They may be moved about and cared for in the same way as the brood. Some ants may bite through tough plant roots so that aphids can find the soft nutritious inner layers but one cannot be sure that this is not an incidental consequence of nest excavation. There is some evidence that some aphids that overwinter in an active state can only survive in ants’ nests where they are protected from fungi and cold. As already suggested they probably supply the ants with easy food at this season. Even the eggs of some species are collected and stored over winter in the nest. Lasius flavus