The very fast spread of the horse-chestnut leafminer Cameraria ohridella throughout Europe has been mainly attributed to a very high dispersal ability combined with wind or human passive transportationover long distances.However, the species effective dispersal characteristics remain to be better understood. Here we present data of experiments aiming to describe the decrease in population estimate as a function of distance to a population source. Firstly, we analysed the decrease in infestation level on horse-chestnut trees along three transect avenues departing from population source located in green areas in Brussels. Secondly, we describe the decrease in catches of pheromone traps disposed along two transects departing from an isolated group of infested chestnut trees. Results of these two experiments suggest that the active dispersal ability might be very short (approx. 100m), and that the largest part of the dispersal could be the result of infested leaves (or fragments) blown from population source during the winter.The evolutionary perspective of this hypothesis (i.e. do leafminers benefit from being dispersed with their leaves) and applied consequences for pest management at the scale of cities is discussed.