Measurements of body size of pollinators
To measure the body size of various pollinators, we captured 10 individual insects of each species visiting the flowers of H. mutabilis during peak flowering. The insect specimens were pinned and dried in a specimen box. Specimens were photographed using a stereoscopic microscope JSZ6S (Nanjing Jiangnan Yongxin Optical Co. Ltd., Nanjing, China) with a digital camera. After imaging, the body length and intertegular distance were measured using ImageJ 1.8.0 software (NIH Image, Research Services Branch, USA) (Fig. 2).