Fig. 2. for affects feeding rate and food acquisition. (A) Gut dissections from larvae fed blue yeast paste for 15 min also indicated that for^R larvae ingested significantly less food than for^s or for^s2 larvae (F_(2,26)=5.32, P<0.05). (B) The rate that the gut filled with food was measured by feeding larvae on a yeast paste with Brilliant Blue dye, extracting the gut, and comparing the length of the gut with food to the length of the entire gut. Gut size did not differ significantly between strains (F_(2,67)=0.86, P=0.43). Sitter (for^s and for^s2) larvae filled their gut more quickly than rover (for^R) larvae (10–20 min feeding, two-way-ANOVA F_(8,36)=70.53 P=0.0008; effect of strain, F_(2,36)=5.82, P=0.007; effect of time, F_(2,36)=5.52, P=0.008; one-way ANOVAs: 5 min, P=0.82; 10 min, P=0.10; 15 min, P=0.05; 20 min, P=0.04). This difference stabilized after about 25–30 min of feeding when the midguts of all larvae become saturated with the blue yeast paste, resulting in no measurable difference in food intake (one-way ANOVAs: 25 min, P=0.85; 30 min, P=0.68). (C) Rovers showed significantly less food intake on fructose–agarose (F_(2,87)=12.20, P<0.0001; for^R vs for^s, P<0.0001; for^R vs for^s2, P<0.0002; for^s vs for^s2, P=0.92) and glucose–agarose (F_(2,87)=3.98, P=0.02; for^R vs for^s, P=0.0078; for^R vs for^s2, P=0.048; for^s vs for^s2, P=0.47) when food intake was measured using Carmine dye. (D) Drosophila larvae use their mouthhooks for both food ingestion and locomotion. We found no significant correlation between mouthhook movements and amount of dye ingested when larvae fed on a glucose–agarose substrate (R²=0.18, P=0.11).