One important mortality factor of Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae) larvae in the trunks of Cryptomeria japonica (L.f.) D. Don (Taxodiaceae) is the presence of oleoresin secreted from traumatic resin canals (TRCs) in the phloem. The present 2-yr investigation examined whether the extent of feeding in the phloem and/or the survival of S. japonicus larvae were negatively influenced by TRCs occurred by Epinotia granitalis (Butler) (Lepidoptera: Tortricidae) larval feeding when these larvae fed simultaneously in the same trunk. The survival of S. japonicus larvae until they reach the xylem, the damage to the xylem, and emergence were investigated. The occurrence of TRCs at the E. granitalis feeding sites was significantly higher at the 1-3-yr-old annual layer compared with nonfeeding sites, suggesting that E. granitalis feeding induces the occurrence. The extent of feeding in the phloem by S. japonicus larvae that were dead there tended to be shorter with number of E. granitalis feeding sites, but the extent of some larvae was long in spite of the existence of E. granitalis feeding, suggesting that larvae feeding opposite to E. granitalis feeding sites could not be influenced by TRCs occurred by E. granitalis. The survival of S. japonicus larvae until they reached xylem did not decrease with the number of E. granitalis feeding sites because preformed TRCs considerably influenced the survival, whereas the survival until damaging the xylem and until emerging decreased. These results indicate that E. granitalis feeding induces the occurrence of TRCs in C. japonica and negatively influences the feeding behavior and survival of S. japonicus, although the survival varies with the feeding direction in respect to E. granitalis feeding sites or the existence of preformed TRCs.