Flight and Attack of the Ambrosia Beetle, Trypodendron lineatum (Oliv.) in Relation to Felling Date of Logs

Log preference of the ambrosia beetle, Trypodendron lineatum (Oliv.) (Coleoptera: Scolytidae), was studied by flight traps, attack density counts, and forced attacks, on 200 Douglas fir felled over a ten-month period. During heavy spring flights in late May, the beetles attacked logs from the August through January fellings, but not those cut February through May. At the end of the first brood-rearing period, parts of logs protected by plastic sheeting from earlier flights were attacked in this same pattern. Beetles confined on logs at different times attacked in essentially the same way as free beetles. It is concluded that felling date greatly influences subsequent attack. However, there was considerable variability in attack within groups of trees cut the same dates. Furthermore, attack on very short (1- and 3-foot) sections from the February fellings, when the corresponding logs were unattractive, showed that a factor other than time of felling also influenced log attractiveness. Some information was secured on flight and attack of other scolytid beetles in relation to felling date of logs.