Allergies caused by the common ragweed, Ambrosia artemisiifolia, impact millions, and in Europe alone, around 13.5 million people suffer with symptoms, resulting in 7.4 billion Euros worth of health costs per year, according to the research. The study suggests the leaf beetle, Ophraella communa, could reduce the number of people affected by the pollen and the associated economic impacts, since the beetle — itself a recent arrival in Europe — loves to munch on the invasive plant.