The species of Cicadidae (Hemiptera, Auchenorrhyncha) from Taiwan are taxonomically reviewed. In this paper, 20 species belonging to nine genera in cicadine tribes, Platypleurini, Tibicenini, Polyneurini, and Dundubiini (subtribe Dundubiina) are included. Cosmopsaltria montana Kato, 1927 is synonymized with Macrosemia kareisana (Matsumura, 1907). Information on the biology and the male chirping of most species including two oscillograms are provided. Information on the distribution of all known species is given.

A total of 22 species belonging to nine genera of the tribes Phenacoccini, Rhizoecini, and Sphaerococcini (Sternorrhyncha: Pseudococcidae) are noted in Korea, with descriptions and illustrations for full grown female. Among them, three species, Heliococcus puerariae sp. nov., Heliococcus zoysiae sp. nov., and Phenacoccus rubicola sp. nov., are new to science, and four species, Coccura comari (Kilnow, 1880), Heliococcus kuriensis Danzig, 1971, Puto erigeroneus (Kanda, 1959), and Puto orientalis Danzig, 1978, are reported for the first time from the Korean Peninsula, and a species is newly known from South Korea. Eleven species, which previously recorded in Korea, have not been found from South Korea during this study.

A taxonomic study of the genus Maladera Mulsant of Korean Sericinae (Coleoptera, Melolonthidae) is presented. As a result, sixteen species are recognized including one new species, Maladera coreana sp. nov., and one subspecies, Maladera castanea koreana subsp. nov. A key, descriptions of the new species and subspecies, and photographs of aedeagus are provided.

A taxonomic review of the genera Serica Mac Leay and Nipponoserica Nomura belonging to the subfamily Sericinae in Korea is presented. As a result, four species of the genus Serica induding two new species, S. hirsuta sp. nov. and S. lutea sp. nov., and two species of the genus Nipponoserica including one new species, N. opacicarina sp. nov. are considered to distribute in the Korean peninsula. The keys to the species, descriptions of the three new species and illustrations of adult's morphological characteristics and aedeagi are provided.

Korean Symmorphus species are reviewed taxonomically. We have confirmed eleven species including six newly recorded ones from the Korean Peninsula: Symmorphus ambotretus, S. angustatus, S. apiciornatus, S. bifasciatus, S. carinatus, S. decens, S. foveolatus, S. lucens, S. mizuhonis, S. murarius, S. tsushimanus. A key, diagnosis, remark and illustrations to all the known species are provided.

The tribe Xanthorhoini of Larentiinae in Korea is reviewed. Eighteen species of eight genera, Scotopteryx Hubner, Costaconvexa Agenjo, Catarhoe Herbulot, Orthonama Aubert, Xanthorhoe Hubner, Euphyia Hubner, Epirrhoe Hubner, and Glaucorhoe Herbulot, are recognized. Four new taxonomic changes are suggested: Scotopteryx golovushkini Kostjuk syn. nov. and S. kuznecovi Herbulot syn. nov. of S. acutangulata Inoue; Microcalcarifera Inoue syn. nov. of Catarhoe Herbulot; and one new combination, Catarhoe obscura (Butler) comb. nov. A key to genera, diagnosis of each species, distribution map and illustrations of adults including male and female genitalia are provided.

감나무에서 문제해충으로 알려진 주머니깍지벌레(Eriococcus lagerstroemiae Kuwana)를 감나무주머니깍지벌레(신칭: Asiacornococcus kaki (Kuwana))로 정정하고, 이들 2종의 정확한 동정을 위해 형태적 특징을 비교하고 도해하였으며, 기주식물들도 포함하였다. Asiacornococcus Tang & Hao, 1995는 한국 미기록 속으로 보고한다.

Fifteen species of the genus Torodora Meyrick (karsholti sp. nov., loeica sp. nov., fuscobasalis sp. nov., epiphorana sp. nov., epitriona sp. nov., spinula sp. nov., longilobella sp. nov., lineata sp. nov., epicharis sp. nov., aritai sp. nov., chumponica sp. nov., pentagona sp. nov., moriyasu sp. nov.; sagmaria sp. nov., and chiangdoica sp. nov.) are described from Thailand, and three species of the genus (flavescens Gozmany, parotidosa Wu, and pegasana Wu & Liu) are reported for the first time from Thailand. The genus Toxotarca Wu is synonymized with Torodora Meyrick. Photographs of the imagos and illustrations of male and female genitalia are given as available.

Three Ethmia species have been found in new materials from Korea: Ethmia comitella Caradja, 1927 (= Ethmia xanthopleura Meyrick, 1931, syn. n.; Ethmia comitella steppella Dubatolov, Ustjuzhanin & Zintschenko, 1997, syn. n.), Ethmia septempunctata (Christoph, 1882), and Ethmia cirrhocnemia (Lederer, 1870) found at the Korea-China border. Taxonomic comments and new distribution data of these three species are given, with illustrations of male and female genitalia.