Monarch butterflies are moving through Texas on spring migration journey KTRK Share: HOUSTON, Texas (KTRK) -- Keep your eyes open for monarch butterflies coming through Texas on their migration to northern America from Mexico, an incredible journey that crosses thousands of miles twice a year. "There's something really special about monarchs and other butterflies that just keeps people interested," said Erin Mills, former director of the Houston Museum of Natural Science's Cockrell Butterfly Center. According to the Center for Biological Diversity, the monarch population reached a historic low in 2017 of fewer than 29,000 butterflies, down from 1.2 million just two decades before.