Mendel, Z., Dept. of Entomology, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Boneh, O., Forest Department, Jewish National Fund, Qiryat Hayyim, Israel
Shenhar, Y., Forest Department, Jewish National Fund, Qiryat Hayyim, Israel
Riov, J., Dept. of Horticulture, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel

The diurnal flight patterns of Orthotomicus erosus (Woll.) and Pityogenes calcaratus Eichh. (Coleoptera: Scolytidae) were studied using funnel traps baited with Pheroprax, the synthetic aggregation pheromone of Ips typographus L. The patterns of the two scolytids were similar and varied between the seasons. In winter, flight occurred only during daylight and peaked at noon (18°C). In spring, flight started when the temperature reached 15°C and two peaks, one in the late morning (20°C) and the other in the early evening (22-23°C), were recorded. In summer, two distinct daily flight periods were recorded: the first peaked in the early morning and the second soon after dusk. The bimodal flight pattern of both species in the warm season reflects hours of optimal flight conditions, viz., when wind speed toward the host tree or breeding material is minimum. © 1991 Springer Science + Business Media B.V.