Significant inter-crop variation in the abundance of phlebotomine sandflies, mostly Lutzomyia verrucarum Townsend, and five aphid species (Hemiptera: Aphididae), was demonstrated by repeated castor oil sticky trap collections in two valleys in the Peruvian Andes. Sandfly populations were significantly higher in fruit crops than in ground crops. Sticky trap collections also proved to be a suitable method for measuring aphid relative abundance in crops. As aphid honeydew is a natural sugar source for phlebotomine sandflies, the relationship between the activities of sandflies and aphids was investigated in inter-crop comparisons. Significant correlations were detected between sandfly abundance and two of the major aphid species, Aphis gossypii Glover and Eriosoma lanigerum (Hausmann), in one valley, but indirect explanations for these apparent associations cannot be ruled out. © 1994, Cambridge University Press. All rights reserved.