Fig. 2. Food consumption (A) and growth (B) in caterpillars maintained for 48 h on the control (N=18), aristolochic acid (Aristo. acid; N=8) or salicin (N=15) diet. The concentrations of aristolochic acid and salicin in the diets are as in Fig. 1. We monitored food consumption indirectly by measuring the total amount of frass (dry mass) produced during each successive 4 h time interval. We monitored growth directly by determining the percentage increase in mass that occurred over the two successive 24 h exposure periods. In A, we compare frass production during the initial 4 h between caterpillars maintained on the aristolochic acid versus control diets (or salicin versus control diets) using the Mann–Whitney U-test (*P0.05). In B, we compare the percentage increase in mass between caterpillars maintained on the aristolochic acid versus control diets (or salicin versus control diets) after 24 and then 48 h of exposure using the Mann–Whitney U-test (*P0.025). All values are medians ± median absolute deviation.