The twobanded Japanese weevil <italic>Pesudocneorhinus bifaciatus</italic> Roelofs, 1879 (Coleoptera: Curculionidae), and the black planthopper<italic> Ricania speculum</italic> Walker, 1851 (Hemiptera: Ricaniidae), which damage a wider range of host plants were investigated for their in-filed occurring pattern during July to October 2024 in the Seonun-ro, Gwangsan-gu and the arboretum of Chonnam National University in Gwangju. <italic>P. bifaciatus</italic> first occurred on July 30 and remained active until October 2, with its peak occurrence observed on September 18. The species was found on four plant species, with the most severe damage to the border privet <italic>Ligustrum obtusifolium</italic>. <italic>P. bifaciatus</italic> was confirmed to attack a previously unreported host plant, the tree of heaven<italic> Ailanthus altissima</italic>. <italic>R. speculum</italic> was observed from July 17 to August 28, reaching its peak on August 7. The species was found on ten plant species, with the most severe damage to the spikenard<italic> Aralia cordata</italic>, the border privet, <italic>L. obtusifolium</italic>, and the chinaberry tree<italic> Melia azedarach</italic> L.. Moreover, <italic>R. speculum</italic> was newly identified on the Korean abeliophyllum<italic> Abeliophyllum distichum</italic>, the oriental chaff flower<italic> Achyranthes japonica</italic>, the spikenard<italic> A. cordata</italic>, the Korean goldenbell tree<italic> Forsythia koreana,</italic> the gardenia<italic> Gardenia jasminoides,</italic> the chinaberry tree<italic> M. azedarach</italic> L., and the Japanese photinia<italic> Photinia glabra</italic> for the first time. The two species were identified using the DNA barcode sequences. Current study provides fundamental insights into the ecology of these two species and serve as foundational data for establishing pest management strategies to mitigate potential damage to several host plants.