The isolation and identification of the title compound was carried out in the following manner: Twenty kilograms of the bark from T. lineatum-infested Norway spruce were collected and put directly into pentane after the entrance holes of boring beetles were thoroughly cut out. After standing for 72 h at room temperature the solvent was removed through a 1-m Vigreux column and the residue was distilled under N z at 15Torr. All volatiles up to 100 ~ were collected, yielding 5.2 g of mainly monoterpene hydrocarbons, oxidized monoterpenes, and sesquiterpene hydrocarbons. GLC analysis was carried out on a Carto-Erba 2100, using a 50-m stainless steel capillary column with Marlophen 87 under program from 50 to I40 ~ at a rate of 3 ~ mass spectra were obtained from a Varian MAT 111 GCMS coupling system. A trace substance (0.2Zo) eluting between 7-terpinene and terpinolene furnished a mass spectrum which strongly resembled the known 1-methyl-6,8dioxabicyclo[3.3.1]octanes [1, 2]: 43 (100), 54 (11), 55 (12), 58 (22), 67 (11), 68 (16), 71 (26), 81 (12), 87 (40), 114 (28), 156 (6, P). Preparative GLC on a Carlo-Erba 2400 with a stainless steel column (8 m, 8 mm i.D., 10% PPG on Chromosorb G AW-DMCS 60-80 mesh) yielded 0.2 mg of the substance, the IH-NMR spectrum (Bruker WH 270, 15,000 scans) of which showed two characteristic signals at b 4.09 (1 H) and 4.21 (1 H), suggesting a bicyclic ketal structure together with the molecular formula C9H1602, obtained by high-resolution mass spectrometry (Varian MAT SM 1). None of the probable 6,8-dioxabicyclo[3.2.1]octane structures which were prepared for comparison were completely in accord with all data of the natural compound. But 1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nouane, a ketal belonging to a bicyclic system recently found in tobacco flavor [3], was identical in all respects with the natural compound. The substance was prepared in low yield by Diels-Alder reaction of 3-buten-2-one and 4-penten-2-ol followed by cyclization. Results of our investigations concerning the exact stereochemistry will be reported later. As the new compound is permanently and exclusively present in Norway spruce attacked by I". lineatum it is now l~ioassayed to clarify whether it serves as a primary attractant beside other chemical messengers such as 3hydroxy-3-methylbutanone [4, 5] and c~-pinene/ethanol [6].