We investigated the distribution, sex ratio, and natural enemies and nesting competition insects of mason bees, Osmia spp. in 32 apple orchards during 2006 to 2008. The rate of bee nested was 14.0±1.7%. The rate of fauna nested were Osmia spp., 66.0%, natural enemies, 21.7% and nesting competition insects, 11.6%. We collected five species of Osmia spp. consisting of Osmia cornifrons, O. pedicornis, O. taurus, O. satoi and O. jacoti. In case of collected five Osmia spp, O. cornifrons was 69.6%, which was the dominant species and O. pedicornis was 13.0% and O. taurus was 11.2%, respectively. The collecting rate of Osmia spp. was significant difference among each year and 10 locations. The sex ratio of Osmia spp. were 1:1.9 in O. cornifrons, 1:5.1 in O. pedicornis and 1:2.2 in O. taurus. The sex ratio of O. cornifrons was significant difference among each year and 10 locations. Seven species of natural enemies that attack Osmia spp. were collected in apple orchard. Trogoderma and Chaetodactylus showed the highest rates with 48% and 38% among 7 natural enemies. Also, we collected nine species of nesting competition insects. Anterhynchium flavomaginatum showed the highest rates with 38.6% among 9 nesting competition insects.

We investigated the distribution and habitat characterization of Korean Osmia spp. in apple orchard of 32 localities during 2005 to 2008. A total of 6,737 Osmia spp. were collected, consisting of six species, which was Osmia cornifrons, O. pedicornis, O. taurus, O. benefica, O. satoi and O. jacoti. The rate of bee nested was 11.7%. Among collected 32 localities, Choongju showed the most collecting rate among other localities, which was 22.4% and 17.5% for Yeongju and 14.9% for Geochang. In case of collected six Osmia spp, O. cornifrons was 60.2%, which was the dominant species and O. pedicornis was 20.4% and O. taurus was 10.8%, respectively. In case of sex ratio, O. cornifrons was 1 : 2.7 and 1 : 5.6 for O. pedicornis and 1 : 2.3 for O. taurus. Osmia spp. was more collected at habitat conditions within apple orchard with plentiful pollens place and abundant water.