Effect of dye concentration on Con-Ex. Control r[A] females consumed 2Y10S3C (A,C,E) or media containing only 1% agar (B,D,F) with the indicated concentrations of Blue 1 (A,B), xylene cyanol (XC, panels C,D), or Blue 2 (E,F). Flies consumed media and excreted waste in the vials for 24 h. ExVial + INT dye was not affected by the concentration of Blue 1 in 2Y10S3C (A) or agar-only media (B) (individual one-way ANOVAs; 2Y10S3C, p = 0.2255; agar-only medium, p = 0.1533; n = 8–20 in panel A and 8 in panel B). ExVial + INT dye was not affected by the concentration of xylene cyanol in 2Y10S3C (C, one-way ANOVA, p = 0.0839, n = 16), but increasing concentrations of xylene cyanol in agar-only media decreased ExVial + INT dye (D; one-way ANOVA, p < 0.0001, n = 8). The concentration of Blue 2 in 2Y10S3C (E, one-way ANOVA, p < 0.0001, n = 16) and agar-only media (F, one-way ANOVA, p < 0.0001, n = 16) significantly increased ExVial + INT dye. Asterisks indicate significantly different pair-wise groups in D,E and F (*Bonferroni’s multiple comparisons, p = 0.0493 to <0.0001).