A pure green sweat bee covers itself in pollen, while pollinating the flower of a squash plant in Canada. Creative Touch Imaging Ltd./NurPhoto via Getty Images Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. For humans, humidity often makes us cranky, sweaty, and downright uncomfortable . For sweat bees, humidity changes their already vibrant colors. According to research recently published in the journal Biology Letters , moisture in the air makes the bees go from blue to green.  “When people think of bees, they often picture drab, brown honey bees,” Dr. Madeleine Ostwald , a study co-author and behavioral ecologist at Queen Mary University of London, said in a statement . “In reality, bees are incredibly diverse and colourful—and we’re only just starting to understand how their appearance reflects the climate they live in.” A sweat bee in the wild. Image: Photo ©Jeremiah Bender.…