ABSTRACT.1The butterflySandia xami(Reakirt) has a very clumped yearly pattern of oviposition on its food plantEcheveria gibbifloraD.C., and the mean number of eggs per plant is always very low.2Three features of host plants are highly associated with the probability of being oviposited upon: height of plant; degree of conspicuousness; and degree of isolation from conspecific plants.3The relative importance of these factors as predictors of the probability of oviposition change according to the time scale considered: height and conspicuousness are more important over short (weekly) time intervals whilst isolation takes precedence over longer (yearly) periods.4It is hypothesized that the clumped pattern of oviposition is responsible for the low numbers of the butterflies relative to their very abundant food plant.