Five species of citrus, including 52 cultivars, were sampled, and field infestations byAnastrephaspp. andCeratitis capitata(Wiedemann) were ranked. Fruit factors including sugar content, pH, thickness and mechanical resistance of the peel, and oil-gland density and volume were measured and compared with infestation levels.A. ludensmade up 98%, otherAnastrephaspp. 1%, andC. capitata, which infested only seven cultivars, 1% of the total infestation. Grapefruits were infested primarily byAnastrephaspp., and tangerines primarily byC. capitata. Significantly more fruit flies emerged from mature than green or half-green fruits. Mechanical resistance, thickness, and estimated oil volume of the peel together were negatively correlated with infestation. For mature fruits, no correlation with infestation, was found between the thickness of the rind or the mechanical resistance of the peel. However, when the data from green and half-ripe fruit also were pooled, there was an inverse correlation between these parameters and infestation levels. The oil volume of the flavedo was inversely correlated with the infestation.