Technical Abstract: The use of olfactory cues for individual nest recognition by the solitary bee Osmia lignaria, the blue orchard bee, was studied in a greenhouse environment. Glass tubes were provided for the bees to use as nesting cavities, so that in-nest behavior could be observed. Also, each glass tube was cut into three sections for removal and replacement of sections for experimental manipulation and then for subsequent chemical analysis. We observed that nesting females drag the abdomen along the tube before exiting, spiraling inside the tube, and sometimes depositing tiny fluid droplets from the tip of the abdomen. For the manipulation, the outer section, the middle section or both sections were removed and replaced with similar clean glass tube sections, and the behavior exhibited by test females was recorded upon arrival in front of the nesting site and inside the nesting tubes. The resulting confusion and hesitation displayed by females after treatments clearly indicated the presence of some olfactory cue used for individual nest recognition inside the entire nest. Chemical analysis of the depositions inside the nesting tube, as well as analysis of the cuticular lipids of the nesting bees, revealed the presence of free fatty acids, hydrocarbons and wax esters.