From a Caltech online article:

When a bee lands on water, the water sticks to its wings, robbing it of the ability to fly. However, that stickiness allows the bee to drag water, creating waves that propel it forward. In the lab, Roh and Gharib noted that the generated wave pattern is symmetrical from left to right. A strong, large-amplitude wave with an interference pattern is generated in the water at the rear of the bee, while the surface in front of the bee lacks the large wave and interference. This asymmetry propels the bees forward with the slightest of force—about 20 millionths of a Newton.

Walking on Caltech’s campus, research engineer Chris Roh (MS ’13, PhD ’17) happened to see a bee stuck in the water of Millikan Pond. Although it was a common-enough sight, it led Roh and his advisor, Mory Gharib (PhD ’83), to a discovery about the potentially unique way that bees navigate the interface between water and air.

To read more: https://www.caltech.edu/about/news/bees-surf-atop-water