Cover Caption

The red imported fire ant, Solenopsis invicta Buren, is an important medical, agricultural, and ecological pest with a global distribution. The main food source of S. invicta is liquid carbohydrates (e.g., plant exudates and honeydew excreted by Hemipterans). This species evolved many strategies to forage droplets of liquid food. The photo shows that S. invicta workers surrounded and fed along the edge of the sucrose water droplet in the field. The diagrammatic sketch (at the bottom of the figure) shows how ants stacked to feed the droplet in the laboratory. After the edge of the droplet was ‘saturated’ by surrounding ants, the stacking ants stepped on other individuals and climbed onto the droplet (see pages 499–507). Blue, red, and green arrows indicate surrounding ants, stacking ants, and incoming ants, respectively. Photo by Wen‐Quan Qin and Qin‐Xi Xie.