French researchers say they are seeing "more and more" areas of mainland France "colonised" by tiger mosquitoes, a species capable of spreading diseases like dengue virus, the chikungunya virus and the Zika virus. Every year from May 1st to November 30th, scientists use entomological surveillance, or egg-laying traps, to assess how established the insect is, and to combat its development. "We're going to have to learn how to limit mosquito densities through these actions, which will be to be to clean our gardens," says Anna-Bella Failloux, an entomologist at the Institut Pasteur. (COMPLETES VIDI33DX9UN_EN) IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES