In April 2026, scientists confirmed sweat bees change color based on weather. These metallic insects shift from deep blue in dry conditions to copper-green when humidity rises. Microscopic structures on their exoskeletons swell with moisture, altering how they scatter light wavelengths. Unlike chameleons, these bees don't control the transformation—it's pure physics. Their bodies act as living hygrometers, passively responding to atmospheric humidity through nanoscale structural changes.