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<i>Endoclita signifer</i> larvae show olfactory recognition towards volatiles of eucalyptus trunks and humus soils. Further, <i>EsigGOBP1</i> was identified through larval head transcriptome and speculated as the main odorant-binding proteins in <i>E. signifer</i> larvae. In this study, the highest expression of <i>EsigGOBP1</i> was only expressed in the heads of 3rd instar larvae of <i>E. signifer</i>, compared with the thorax and abdomen; this was consistent with the phenomenon of habitat transfer of 3rd instar larvae, indicating that <i>EsigGOBP1</i> was a key OBP gene in <i>E. signifer</i> larvae. Results of fluorescence competition binding assays (FCBA) showed that <i>EsigGOBP1</i> had high binding affinities to eight GC-EAD active ligands. Furthermore, screening of key active odorants for <i>EsigGOBP1</i> and molecular docking analysis, indicated that <i>EsigGOBP1</i> showed high binding activity to alpha-phellandrene in 3rd instar larvae of <i>E. signifer</i>. Conformational analysis of the <i>EsigGOBP1</i>-alpha-phellandrene complex, showed that MET49 and GLU38 were the key sites involved in binding. These results demonstrated that <i>EsigGOBP1</i> is a key odorant-binding protein in <i>E. signifer</i> larvae, which recognizes and transports eight key volatiles from eucalyptus trunk, especially the main eucalyptus trunks volatile, alpha-phellandrene. Taken together, our results showed that <i>EsigGOBP1</i> is involved in host selection of <i>E. signifer</i> larvae, which would aid in developing <i>EsigGOBP1</i> as molecular targets for controlling pests at the larval stage.