On our patio we have strawberry plants in pots. For the past two years we have noticed that large numbers of ants systematically bring small bits of dirt, gravel and woodchips, and pile them around the bases of the plants and their runners (see Photo). It seems they are cultivating the plants. When the strawberries are grown, however, the ants do not always eat them, but sometimes bury them. The plants seem to thrive 鈥� what is going on?
Lisa and Tom McIlwain, Portland, Oregon, US