The genus Periphyllus has been revised as seven species in the Korean Peninsula. Recently, Periphyllus hokkaidensis Sorin 1990 is newly discovered on the young shoot of Acer mono subsp. okamotoanum in Ulleung Island. This is the first record found P. hokkaidensis in other areas except Hokkaido, its origin region. As the result of this study, we announce totally eight species in this genus and present description and illustration of P. hokkaidensis with apterous viviparous females.

The genus Periphyllus is tree-dwelling group, mostly on maple tree (Acer spp.). In this study, we discovered one species new to Korea, P. loricatus (Pashtchenko 1987) on A. ginalla. In prior to Pashtchenko(1987), Periphyllus ginallae Paik in Szelegiewicz (1974) seems the same species, nevertheless, treated as 'nomen nudum' without any description. As a result of our revision, totally seven species belong to this genus in the Korean peninsula.

Metcalfa pruinosa (Say) (Hemiptera: Flatidae), the citrus flatid planthopper(CFP) is suddenly discovered this year in Seoul and Gyeonggi Province, Korea. CFP is originally distributed in the Eastern parts of North America(Metcalf and Bruner 1948), and recently spreading to European countries(Baker et al. 2008) such as northern Italy, Spain, and France. It is an economically important plant-sucking insect having wide host range including many agricultural crops such as grapefruit and citrus, and ornamental trees, camellias, azaleas, and magnolias(Dean and Bailey 1961) mediating plant viruses. We discovered large samples on Hosta longipes (Franch. & Sav.) Matsumura, Liriope platyphylla F.T.Wang & T.Tang, Weigela subsessilis L.H.Bailey, etc. in Seoul and Suwon on August 2009. In this report, we announce their taxonomic position, morphological characters, distribution, host information, and importance as a possible pest in the Korean peninsula.

The members of the genus Chaitophous(Hemiptera: Aphididae) has limited host specificity on two genera of the family Salicaceae, Salix and Populus. In this study, as a result, we discovered 5 species new to Korea: C. Horii Takahashi 1939, C. leucomelas Koch 1854, C. salijaponicus Essig & Kuwana 1918, C. tremulae Koch 1854, and C. populialbae yomefuri Shinji 1941.

The soybean aphid, Aphis glycines Matsumura 1917, is well known as a soybean pest in the world. Recently, it has been introduced to North America causing serious damage in U.S. As a cooperative research with USDA-ARS, we have investigated A. glycines in soybean fields, and also examined the colonies on the overwintering host Rhamnus davurica in order to find its natural enemies. It was generally reported that A. glycines has host alternation between the soybean, Glycine max (summer host) and the Dahurian buckthorn, Rhamnus davurica (winter host) in East Asia. However, it was very difficult to identify the soybean aphid, A. glycines, from R. davurica due to the co-existance of at least three Aphis species and the seasonal polymorphisms of each species (e.g, gynopara, ovipara, and male). For species identification, we tested 3 molecular markers, mitochondrial COI, COII, and nuclear EF1α, for 14 collected samples (7 samples from G. max and 7 samples from R. davurica). As a result, we found two different species, A. gossypii and other Aphis sp., are mixed together with A. glycines on R. davurica. We report the biology of A. glycines in Korea, and present species identification using molecular phylogenetic approach.