Damage due to leaf mining by Liriomyza trifolii (Burgess) is a major problem in many leafy vegetables, especially lettuce. A hierarchy of feeding preference of leafminer on lettuce, Lactuca sativa L. cultivars 'Valmaine', `Parris Island Cos', `Floricos 83', and `Tall Guzmaine' was determined. Leafminers were given a choice of two plants. Observations on the number of times that leafminers probed the leaf surface to feed or oviposit in each plant was counted. `Tall Guzmaine' was significantly preferred in all combinations. Probe ratio of `Tall Guzmaine' verses the other cos lines ranged from 4:1 to 90:1. There were no significant difference between the other three lines, although `Valmaine' had the lowest count in most cases. Based on the pedigrees of the cultivars tested, the observed preferences appears to be under genetic control.