Bees of the genus Osmia are cavity-nesting solitary species that play important roles as pollinators. Nest traps are one of the most common methods to study Osmia bees. To elucidate the optimal environmental conditions of nesting sites, we investigated the effects of location, direction, altitude, and sites of nest traps on the rate of trap-nesting Osmia spp. During the collection period, the average rate of trap-nesting Osmia spp. collected within 90 days after the installation of traps was 17.0±20.0%. This percentage was 2.7-fold higher than that of trap-nesting bees in 30 days after the installation of traps. The Jeongseon location exhibited the highest rates of trap-nesting Osmia spp. collected in 30 and 90 days, representing 11.1 ±17.6% and 23.2±22.5%, respectively. The direction of the nest traps did not affect the rate of trap-nesting Osmia spp. The altitude ranges of the traps were 0-199 m, 200-399 m, 400-599 m, 600-799 m and over 800 m. Interestingly, the altitude range of 600-799 m showed the highest rate of trap-nesting bees, which was 40.4±3.9%. Higher altitudes seemed to correspond to higher rates of trap-nesting bees. With regards to the sites where the nests were placed, the rate of trap-nesting bees in a mud wall of an old house was 45.1±25.2%, which was 3-fold higher than that of a nest in an apple orchard. The flowering plants collected at different locations during the trap-nesting activity of Osmia bees belonged to 18 families and 34 species. In conclusion, the rates of trap nests colonized by Osmia spp. were affected by altitude, site, and plant diversity.

In order to improve mass rearing methods of hornfaced bee, Osmia cornifrons, in different field condition, a series of studies were conducted in apple orchard in Geochang province, eco-park in Suwon and botanical park in Yongin. 1,000 individuals and 2,000 individuals of Osmia cornifrons were released apple orchard and eco-park and botanical park respectively. Nesting rate of Osmia conifrons was most effective in case of releasing in botanical park in Yongin with 38.2% and lowest in eco-park in Suwon with 21.7%. And also number of cocoons nested in bamboo tube traps was highest in botanical park in Yongin with 3,494 individuals. Sex ratio in 3 different areas was also most effective with 58:42 in botanical park, 50:50 in apple orchard and lowest with 43:57 in eco-park. Nesting activity was shown starting point in 20th day, peak point in 38th day and ending point in 46th day after releasing of adults. This result shows nesting efficacy in botanical park designed with various species of plant sources pollinating insect, Osmia cornifrons, to increase the multiplication rate in field condition is more effective than other areas. General type of nest shows same tendency in efficacy of nesting rate compared with specific type of nest designed with dark thick cover in apple orchard. But it's result needs some further examination in same condition.