Monarch butterflies are some of the more beloved critters in the insect class, but each year they face a perilous journey as they migrate between North and Central America. According to a BBC report, a recent study from scientists at the University of Washington reveals how the tiny creatures navigate the migration with a complex internal compass.

According to the study’s lead author Professor Eli Shlizerman, a mathematician from the University of Washington, “Monarch butterflies complete their journey in such an optimal, predetermined way. They end up in a particular location in Central Mexico after two months of flight, saving energy and only using a few cues.”

In collaboration with a crew of biologists including Steven Reppert of the University of Massachusetts, the team gathered data straight from neurons in the butterflies’ antennae and eyes. They were surprised to learn that the sun played a significant role in guiding the butterflies along their migratory journey.

“One is the horizontal position of the sun and the other is keeping the time of day. This gives the insects an internal Sun compass for traveling southerly throughout the day,” said Shilzerman.

The scientists created a model simulating the internal compass using two mechanisms. They simulated the neurons found in the butterflies’ antennae, as well as the neurons found in the butterflies’ eyes, or azimuth neurons, which monitor the location of the sun in the sky.

According to Professor Shilzerman, the model circuit receives inputs from the two simulated neurons to triangulate the position of a butterfly relative to the sun. He says that the model helps shed new light into the butterflies’ behavior as they make their massive journey south and back each year.

“It’s a very interesting application that could follow the butterflies and even help maintain them,” he said. “Their numbers are decreasing, so we want to keep this insect – the only one that migrates these huge distances – with us for many years.”

A press release from the University of Washington describing the details of the study can be found here.