Fluctuating asymmetry (FA) is a widely used tool to detect developmental instability and plants under stressful conditions are expected to exhibit increased values of asymmetry, as well as higher levels of herbivory. This study evaluated whether dust from roads can cause major deviations in the axis of symmetry of leaves of the pioneer plant species Cecropia pachystachya Trécul (Urticaceae). It was also investigated whether plants exposed to dust have greater nitrogen content and higher levels of herbivory levels. Ten leaves of 20 individuals of C. pachystachya were collected on two roads with different levels of dust deposition and a control area. FA was calculated as the size-scaled difference between the right (RW) and left (LW) leaf widths and leaf area removed was determined by the ratio between leaf area removed and total leaf area. C. pachystachya plants in areas under strong influence of dust pollution exhibited the highest FA values (0.279 cm), whereas plants in the control area exhibited the lowest. A positive relationship between levels of leaf area removed by insects and a gradient of dust pollution was also observed. Differences in foliar nitrogen concentration among sampling areas indicated differences in leaf quality and influenced herbivory levels of Cecropia. This study indicated that FA can be used as an indicator of developmental instability of plants and those individuals under the impact of road dust and pollution might be more susceptible to insect attack.