| Summary: | <i>Holotrichia parallela</i> (Coleoptera: Scarabaeidae: Melolonthinae) is a notorious pest of many crops, especially peanuts. In this study, volatiles from peanut plants were analyzed using both gas chromatographic-electroantennographic detection (GC-EAD) and gas chromatography/mass spectrometry (GC/MS) techniques, and tested for adult attraction with field trapping bioassays in Hebei Province, China. GC-EAD analyses indicated that <i>H. parallela</i> antennae strongly responded to twelve GC peaks, including eight identified compounds, (<i>Z</i>)-<i>β</i>-ocimene, hexanal, 6-methyl-5-hepten-2-one, nonanal, dihydromyrcenol, linalool, <i>β</i>-caryophyllene, methyl salicylate, and four unidentified compounds. When tested individually in field conditions from 24 to 31 July, 2020, <i>β</i>-caryophyllene and hexanal significantly attracted both sexes of <i>H. parallela</i>, whereas all other compounds were unattractive. A blend of <i>β</i>-caryophyllene and hexanal at a ratio of 2:1, close to the natural ratio of these two compounds from the intact peanut plant, was most attractive to the beetles. The remaining identified compounds, (<i>Z</i>)-<i>β</i>-ocimene, 6-methyl-5-hepten-2-one, nonanal, dihydromyrcenol, linalool, and methyl salicylate had no synergistic effects on <i>H. parallela</i> attraction when tested in combination with the blend of <i>β</i>-caryophyllene and hexanal. These results demonstrated that <i>β</i>-caryophyllene and hexanal in the volatiles from peanut plants have strong attraction to <i>H. parallela</i>. These two compounds have the potential to be used for monitoring <i>H. parallela</i> and its management programs.
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