In the Paüls area, different ravines converge that end up flowing into the Ebro river. In the upper and middle part of these ravines we find a more or less constant water circulation, with areas with running water, areas where the water remains stagnant. by the very orography of the ravine and areas where surface water disappears.
The black fly problem in this area has its origin in two factors: on the one hand, the development of larvae in specific areas of the nearby ravines, where the water current is constant and allows the development of these larvae, as is the case of different points of the Montsagre, Molino and Las Fuentes ravine; and on the other hand, we must take into account the proximity of the municipality of Paüls to the river Ebro, since the little more than 7 km that separate them is an easily accessible distance for adults who develop in the river.
Sampling: the sampling carried out in this area to detect black fly larvae is based on the observation of the macrophytes found in the riverbed, mainly of the genus Nasturtium (watercress), on top of the leaves or stems on which they are attached. the lavas and pupae of the black fly.
Control: it is carried out manually by applying Bti with the help of a backpack where the product is mixed with the necessary water to obtain an adequate concentration of product and a volume of the mixture that allows us to apply the product for a certain time . The little circulating flow as well as the irregularity in the current, alternating in areas with surface water with a certain current and areas without current or with underground circulation, mean that the amount of product applied in each case is determined by the application time, which depending on the points it can vary between 2 and 4 minutes.
