The monarch butterfly sanctuaries in the states of Mexico and Michoacan opened their doors Saturday to tourists.

The Secretariat of Environment and Natural Resources said the sanctuaries would remain open till March 31, 2016, so that visitors could get to know the species.

The butterflies traveled over 4,000 km from Canada and the United States to arrive at their final destinations in Michoacan and the state of Mexico.

The butterflies, half a gram in weight, will stay in Mexico for four months during their breeding phase.