By Francesco Tomasinelli & Emilio Scoti

In the limestone hills between Texas, New Mexico and Mexico lies a wide cave complex with the biggest bats colonies of the world. Frio Cave, in Southern Texas, is one of the most spectacular, holding more than 10 millions of free tail bats, Tadarida brasiliensis. Each evening, during spring and summer, they emerge all together from three holes on top and flank of the cave to go hunting insects. There are so many of them than they take about 30 minutes to come out, generating one of the most incredible nature shows on the planet. These pictures are special because they were taken inside the cave with special permits (you are allowed only a few minutes and without any "strong light" equipment) and special equipment, since the air is toxic because of bats droppings.

Special thanks to Bat Conservation Iternational and to Jonah Evans for their precious help