Obliquebanded leafroller, Choristoneura rosaceana (Harris) is a polyphagous totricid commonly found in wild habitats. Since commercial apple orchards replaced large amounts of native vegetation, this insect causes damage to fruit when it feeds and has become a serious pest of apples. The objective of this study was to investigate whether the host plant influences larval fitness. Host plant effects on larval development time, pupal weight and on fecundity were tested using apple and gray dogwood as hosts. Caterpillars were collected from both host plants and were offered both apple and dogwood leaves. Pupae of females originating from dogwood were larger, however this effect did not translate into higher fecundity. Females that fed on dogwood required more time to reach pupal stage, suggesting nutritional differences between the two host plants. Host plant effects on larval settlement rate and on natural enemy inflicted larval mortality were studied by releasing sentinel caterpillars on potted apple trees and native dogwood plants. Larval settlement rate and mortality due to natural enemies or natural dispersion did not significantly differ on the two host plants. The 4 most important parasitoid species: Oncophanes americanus (Braconidae), Exochus albifrons (Ichneumonidae), Actia interrupta (Tachinidae), Mateorus trachynotus (Braconidae) parasitised the same proportion of larvae on the 2 host plants. Another important parasitoid, the Colpoclypeus florus (Eulophidae) parasitized a significantly higher proportion of larvae on apple than on dogwood.