The black fly has arrived in Madrid with force and its presence has become especially noticeable in the area around the Manzanares River and other riverside areas of the region. This insect, which measures only between 3 and 5 millimeters, has become a problem for neighbors and passers-by, since its bite is painful and can cause inflammation, intense itching and, in some cases, allergic reactions that require medical attention. The increase in population in recent years, according to the Community of Madrid, is due to a “slight improvement in the quality of river water due to the purification of discharged wastewater”.
Where is the black fly in Madrid?
The most affected areas are the course of the Manzanares river as it passes through the city, with critical points in El Pardo, the Caja Mágica, the Club de Campo and Playa de Madrid. There are also cases in the confluence of the Henares and Jarama rivers, affecting municipalities such as Alcalá de Henares, Arganda del Rey, Coslada, Mejorada del Campo, Rivas-Vaciamadrid, Torrejón de Ardoz and Aranjuez.
Unlike mosquitoes, the black fly is diurnal, bites rather than stings (it injects an anesthetic that prevents the attack from being noticed immediately) and usually attacks in areas of exposed skin, even under clothing. Only females bite, and they do so to complete their reproductive cycle. Although they do not transmit diseases, the reaction to their bite can be annoying.
What is Madrid doing to combat the black fly?
The delegate of Urbanism, Environment and Mobility of the City Council of Madrid, Borja Carabante, has announced through the social network X (former Twitter) some of the measures put in place to combat this pest. This year it has reinforced its control campaign in the Manzanares, with an annual investment of 2.5 million euros and 40% more samplings compared to previous years. Biological treatments are applied with the larvicide, which acts only on the larvae of the black fly without affecting other aquatic species.
In addition, aquatic vegetation clearing and entomological analyses are carried out to monitor the effectiveness of the interventions. According to their data, thanks to these measures, the presence of the black fly has been reduced by 86% in the treated areas.
Tips to avoid black fly bites
Health authorities recommend extreme precautions in areas near rivers between May and October, use repellents (preferably with citronella), wear light-colored, long-sleeved clothing, and avoid contact with aquatic vegetation. If you suffer a bite, do not scratch the area, apply local cold and go to the doctor if the inflammation is intense or allergy symptoms appear.