The effect of early-arriving attackers on the interaction between later-arriving, co-occurring attackers. (a) The mean mildew coverage when mildew co-occurs with aphids (5) and when caterpillars arrive earlier than the co-occurring mildew and aphids (14). (b) The mean mildew coverage when mildew co-occurs with a caterpillar (6) and when aphids arrive earlier than the co-occurring mildew and caterpillar (15). (c) The mean aphid population size when aphids co-occur with mildew (5) and when caterpillars arrive earlier than the co-occurring aphids and mildew (14). Each treatment had 20 replicates, and error bars present the standard errors. Significant differences between treatments in each week are indicated by letters above the bars. For statistical models and estimates, see electronic supplementary material, tables S3, S7, and S8. (Online version in colour.)