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The giant water bug, Lethocerus deyrolli, is an endangered wetland insect found throughout East Asia. In 2006, the light-attraction flight of L. deyrolli was studied in Gyodong Island, Korea, using artificial light. The flight of L. deyrolli was observed from early June to late October, and two peaks in the numbers of attracted insects were noted in the middle of June and September. L. deyrolli begins to exhibit flight behaviour at a daily mean air temperature of 15°C and above, but optimal flight temperatures for the insect are between 17°C and 19°C, with a wind speed of less than approximately 1.8 m/sec and a relative humidity of around 80%. The length of daylight did not substantially influence the flight pattern. Daily flight occurred principally between 9 pm and 10:30 pm. L. deyrolli individuals attracted by the artificial light were frequently consumed by magpies or house rats. It appears most probable that artificial lights, such as street lights and tennis court lights, constitute a critical factor in the local extinction of L.deyrolli. [ABSTRACT FROM AUTHOR]

In this study, we investigated the life history of Ephemera orientalis, a common lowland burrowing mayfly which resides in temperate East Asia and often causes a serious nuisance to people due to mass emergence from the Han River in Seoul, Korea. Larvae were sampled monthly (every two weeks during the emergence period) from April 2006 to June 2007 using a Surber sampler (50 × 50 cm, mesh 0.25 mm, two replicates). The mean density of E. orientalis was found to be 105.88±42.14 indiv/m2 during the study period. On the basis of the larval body size distribution and emergence time, we concluded that E. orientalis has a univoltine life cycle with two distinct cohort groups, S1-group emerging in May-June and S2-group in August-September. The estimated annual production of the larvae was 1350.84 mg DW/m2; the mean biomass was 325.17 mg DW/m2; the annual production to mean biomass ratio (P/B) was 4.15. Mean water temperature during the study period was 15.02±6.84°C. The accumulated degree days for the S1- and S2-groups were 2565.07 and 2,621.69 degree days, respectively. This study shows that the Han River population of E. orientalis lacks the fast growing cohort (F-group) in May-August, and demonstrates a relatively higher secondary production than that of other stream mayflies (e.g. Gapyeong stream population of E. orientalis). [ABSTRACT FROM AUTHOR]

The genus Ephemera Linnaeus, the type genus of the family Ephemeridae and the order Ephemeroptera, began to be studied as early as in the nineteenth century, but the East Asian species of Ephemera remained poorly understood. In this paper, 16 Ephemera species from tropical Southeast Asia are reviewed and descriptions of new or poorly known species and life stages, synonyms, reference sources, type information, taxonomic remarks, a male adult key to the species, and a tabulated checklist of the species are provided. Ephemera mccaffertyi sp. n. from Malaysia is described. Ephemera hainanensis Zhang, Gui & You, E. rufomaculata Zhou & Zheng, and E. spilosa Navás are redescribed. The larval stage of E. hainanensis and E. spilosa are described. Ephemera innotata Navás, E. javana Navás, E. longiventris Navás, and E. quadrigutata Lestage are assigned as nomina dubia. As a result of this study, four species from Vietnam, four species from Myanmar, two species from Thailand, one new species from Malaysia, and three species from Taiwan have been identified as members of the genus Ephemera. [ABSTRACT FROM AUTHOR]