Giant Bagworm Moth, Clania variegata Snellen, which caused severe damage to orchard and forest trees was first found and recorded by the author in Korea. The binomics and morphological characteristics of this species were presently studied from 198o to 1985 in Suncheon area, Chonnam in Korea. In addition, its geographical distributions were observed throughout the country. This species was univoltine and overwintered as the mature larvae, pupated from mid-April to mid-June and emerged from mid-May to late July. They oviposited soon after emergence and began to hatch from late June. Pupation of males was ca 10 days earlier than that of females, whereas female emergence was ca 5 days earlier than male emergence. This biological phenomena resulted from the different pupal period between males and females, namely, average 29.2 days for males and 14.8 days for females. Emergence peak of males was on June 26th and that of females on June 11th in 1982. Most of males emerged from the late morning to the afternoon, and the adult longevity was average 12.6 days for females and 2.2 days far males. The average numbers of eggs deposited in the field conditions were ca 2828 and oviposition period was ca 27.2 hours, while egg period was ca 19.9 days, and percent hatching was ca. 88.6. The larvae were more active at night than at day-time, and also larval bags were enlarged as larvae grew until they became 8th instar. Mature larvae entered overwintering earlier when food was absent at the lower temperature of -3℃. Also overwintering larvae observed in the field in December varied from 5th to 8th instars. Thus overwintering larvae appears to be related to the feed and temperatures rather than instar maturation. Overwintering bags were examined to determine: factors associated with population reduction during winter season. The related factors were more; significant in the following orders; unknown mortality bags $gt; last year bags $gt; falling bags $gt; parasitized bags. Among these bags, unknown mortality bags were increased dramatically after December, whereas empty bags were found considerably in November, but rarely increased afterwards. In the field condition during winter and constant low temperatures of 2℃, - 10℃ and - 15℃, the mortality numbers of female: larvae were much larger than those of males. Percent reduction of body weight was also much larger in females than in males, but body lengths were fairly similar in the two sexes. Therefore larger mortality in females appears to be related to reduction of body weight due to water loss.