The two-spot coccinellid (Adalia bipunctata (L.)), will feed on a variety of aphid species but is usually associated with those living on trees or shrubs greater than 2 m in height (Putnam 1964; Iperti 1966; Hodek 1966). In Glasgow, larvae of this predator are common on lime (Tilia x vulgaris Hayne), where they feed mainly on the aphid Eucallipterus tiliae and less often on the cicadellid Alnetoidea alneti Dahlbom. A. bipunctata occurs less frequently on sycamore (Acer pseudoplatanus L.), where its effects on populations of the aphid Drepanosiphum platanoides (Schr.) were described by Dixon (1970). The numbers of the lime aphid fluctuate markedly within a season and from year to year (Dixon 1971), but the role of coccinellid predation in these changes is unknown. This paper attempts to assess the searching capacity and survival of the predator on lime, and to evaluate the role of the two-spot coccinellid in the regulation of the numbers of the lime aphid.