This study identifies the volatile organic compounds (VOCs) emitted by citrus when infested with California red scale (Aonidiella aurantii) and determines which of these elicit behaviour responses in the predator Rhyzobius lophanthae. Headspace solid-phase micro extractions (HS-SPME) technique combined with gas chromatography-mass spectrometry (GC-MS) was used to identify compounds and Y-tube olfactometer to determine R. lophanthae behaviour responses. According to the results, 22 VOCs were detected in infested citrus plants and some of them were increased in lemon, orange and tangerine by A. aurantii infestation. R. lophanthae individuals were attracted to infested citrus saplings. According to bioassays with the olfactometer, they were attracted to methyl salicylate and D-limonene at dosages of 1 and 10 mu L/mL by using a Y-tube olfactometer. These results explain how citrus volatiles can affect the response of the predator R. lophanthae.