Each fall, monarch butterflies take off from as far away as Ontario and fly to central Mexico where they overwinter. Now, for the first time, scientists can track individual monarchs along this epic journey.

That’s because of a 60-milligram, solar-powered radio tag that’s attached to select butterflies. The monarchs, which weigh between 500 and 600 milligrams, are then tracked on a cellphone app developed by the tag manufacturer.

Butterfly aficionados can also follow individual monarchs on a free app called Project Monarch Science. They can plant pollinator gardens, too, which help nourish butterflies along their route.

This technology will hopefully provide crucial data on hundreds of species of butterflies at a time when they need all the help they can get.