The honeydew-producing treehopper, Guayaquila xiphias, is frequently tended by ants on shrubs of Didymopanax vinosum in the Brazilian savannah. Field experiments showed that the flicking of accumulated honeydew by untended treehoppers provides cues to ground-dwelling ants. Upon finding scattered honeydew droplets on the ground, the ants climb onto the host plant and start tending activity. Honeydew-soaked filter papers placed beneath unoccupied host plants induced significantly more ants to climb onto the plant than water-soaked papers. Because predation and parasitism on G. xiphiascan be severe at early stages, and tending ants protect the homopterans against predators and parasitoids, the capacity to attract ants early in life can be crucial for treehopper survival. ? 1996 The Association for the Study of Animal Behaviour Phloem-feeding Homoptera (primarily aphids, membracids and scales) are commonly tended by ants that harvest their energy-rich honeydew (Auclair 1963; Way 1963). Homopteran honey- dew is generally regarded as an ant attractant (Sudd 1987), and tending ants can provide a range of benefits to homopterans, including protection from natural enemies (Buckley 1987a, b, and ci- tations therein). Ant colonies may simultaneously tend many homopteran aggregations, and intra- and interspecific competition for the services of ants can adversely aVect homopteran fitness through reduced tending levels (Cushman & Addicott 1989; Cushman & Whitham 1991). Pre- dation pressure on homopteran aggregations can be severe at early developmental stages, and ant tending can greatly increase the number of surviv- ing nymphs (Bristow 1983; Cushman & Whitham 1989). Therefore, the capacity to attract ants early in life can be crucial for the survival of ant-tended homopterans, especially under low ant densities (Cushman & Addicott 1989).