Movie S1.

Light sensitivity behavioral assay designed to test whether ectopic eye-like structures (EELS) are sufficiently complex to support functional integration with the rest of the organism. In this assay, an individual beetle is placed inside a dish in a dark room and allowed to walk; a cold bright, flickering light is then shone in front of the beetle. Wild-type individuals (B−I−) react without exception by stopping, lowering their heads, turning around, and quickly moving away from the light source. In contrast, eyeless wild-type beetles (B+I−) invariably fail to show any reaction to light. Eyeless otd1RNAi individuals possessing EELSs but lacking lateral compound eyes (B+I+) eventually react to the light stimulus by either lowering their head or turning around, or a combination thereof. Typical responses for each treatment are shown: 00 min:00 s, untreated wild-type B−I−; 00 min:15 s, eye-ablated wild type; 01 min:07 s, eye-ablated, otd1RNAi with ectopic eyes.