Figure 1.

The effect of changes in horizontal optic flow cues in the tunnel on the groundspeed of M. genalis (black boxes) and B. terrestris (grey boxes). Box limits represent the 25th and 75th percentiles of the data, dotted lines indicate the median, whiskers extend to the rest of the data, crosses indicate outliers. Both species increase their groundspeed when horizontal motion cues are minimized, but unlike Megalopta, bumble-bees do not fly faster when horizontal motion cues are removed from one wall. Significance codes: **p < 0.01; ***p < 0.001; n.s., not significant.