This study was conducted to investigate specific stages and distribution of overwintering nymphs of green rice leafhopper, Nephotettix cincticeps by measuring head capsule width. The nymphal head capsule width of the 1st instar to the 5th instar was 0.381, 0.502, 0.673, 0.979 and 1.128 ㎜, respectively. Its coefficient variation was 5.3, 4.0, 3.0, 4.5 and 5.3%, respectively. Growth ratio of each instar was not significantly different among 2nd to 4th instars as 1.31 to 1.34, but for the 5th instar it decreased as 1.28. The logarithm of the nymphal head capsule width was regressed as a function of the stage number of insects, resulting in LogY = 1.4627 + 0.1192X (r² = 0.9993). Also fitness to the Dyar’s law for the nymphal head capsule width of each instar was 98% or over and the Dyar’s constant (K) was 1.316. The occurrence of N. cincticeps was maximum at the end of January with 195 individuals/0.25 ㎡. The most abundant instar in the overwintering N. cincticeps population was 4th instar accounting for over 90%. Population of the 5th instar began to increase from mid-March, and adults began to occur in early April.

Determining age distributions of insect is required for many basic ecological studies. Most of insect developmental studies, the head capsule width and other developmental traits have been widely used to distinguish the instars. Unlike to other insect species, collembolan continues to molt after they reach sexual maturity. So these traits sometimes make it difficult to conduct developmental studies. Model animal used in this study was Paranura rosea a native collembolan speciese. To determine the age groups of P. rosea, we periodically (1week) made digital images of P. rosea (over 100 different images) under the magnifier (DIMIS-M) for consecutive 20 week. And then the head capsule width and the surface area of P. rosea were analyzed using a image software (ImageJ). In this test the head capsule widths and surface area were set as developmental parameters. Both two developmental parameters showed time-dependent increase patterns. And they gave good agreements between predicted developmental parameters and observed parameters (r2=0.83 and 0.71). Based on the reproducibility of juveniles and statistical mean separation tests (tukey's test), both two developmental parameters could be divided into 3 age groups. The information given this study will be used as a basis for understanding the population dynamics and other ecological research.

완전 변태류 곤충에 있어서 각유충기의 구분은 두폭에 의하는 것이 상례이다. 그러나 분포의 특성이 정의되지 않는 재래적 방법으로는 객관성이 보장되지 못하며 때로 령기의 판정조차 어려울 경우가 있다 이러한 단점을 보완, 각 령기의 두폭분포의 특성을 통계적으로 기술하기 위해서 "d/w"비의 개념을 도입하는 것을 검토하였다. 쌀바구미 유충의 두폭분포를 이 비를 이용하여 정의하였으며 이러한 예는 다른 곤충의 경우에 있어서도 합리적으로 적용될 수 있음을 보여주는 것이라 사료된다.