In 2020, severe defoliation was reported in Abies holophylla plantations located in Hwacheon-gun, Gangwon-do. This damage was attributed to an outbreak of an unidentified sawfly species from the genus Cephalcia (Hymenoptera: Pamphiliidae). The larvae of this sawfly caused significant defoliation of the leaves. This pest has been identified as Cephalcia koreana Park & Jung, sp. nov., described as a new species in 2023. To investigate the occurrence pattern and density of C. koreana, we set up emergence traps and analyzed samples from affected branches. Our results showed that the density peaks for adults, eggs, and larvae were in mid-May, late May, and early June of 2021, respectively. However, their density decreased sharply after a notably cold spring period in 2022. Here, I aim to discuss the outbreaks of insect pests and their population dynamics.

Monitoring was conducted to investigate the occurrence of Grapholita dimorpha Komai in Korean apple orchards using sex pheromone traps. G. dimorpa showed four peaks per year: early May, from late June to early July, from late July to mid August, and from late August to September. After adult emergence of the over-wintered G. dimorpha, G. dimorpha catches was decreased significantly and increased again after July. In G. molesta traps, G. molesta and G. dimorpha were trapped by 98.8 and 1.2%, respectively. Conversely in G. dimorpha traps, G. dimorpha and G. molesta were trapped by 99.7 and 0.3%, respectively. The 30.6% of the moths from the damaged apple fruits were G. dimorpha. This is the first report on G. dimorpha in apple orchards in Korea.

Major fruit moths in commercial apple orchards are known as Carposina sasakii and Grapholita molesta. In addition, recently G. molesta is dominant species compared with C. sasakii in apple orcahrds. In case of Japan, the fruit damage occurred a lot unexpectedly in apple orchards of the northern Nagano during the harvesting season in 2004. As the result of identifying after emerging the larvae collected from the damaged fruit, Grapholita dimorpha was found out. The morphology of Grapholita dimorpha are almost similar to that of Grapholita molesta, and the shape of the damaged fruits was too similar to distinguish them. We installed sex pheromone traps of Grapholita dimorpha in apple orchards to check if there were Grapholita dimorpha in Korean apple orchards and to survey seasonal occurrence. As a result of survey by installing sex pheromone traps of G. dimorpha at one apple orchard in Uiseong-Gun and Gunwi-Gun area respectively, we could find high population density of G. dimorpha in sex pheromone traps. The peak of the first generation of G. dimorpha was dated in early May. The first generation occurrence of G. molesta in sex pheromone traps was lower than that of Grapholita molesta. However, it had higher occurrence of sex pheromone traps than G. molesta since it increased after mid and late July. Also, as a result of identifying in G. molesta traps, there were 673 G. molesta and 8 G. dimorpha. As a result of survey of 1,102 G. dimorpha in its sex pheromone traps, there were 1,099 G. dimorphaand 3 G. molesta.