Coloration in Nephotettix cincticeps is usually green. However, individuals which have blue coloration are occasionally found in the field. Blue-type can easily be distinguished from normal-type even in the nymphal stage since coloration of blue-type nymphs is white and that of normal-type ones is yellow. There was no significant difference in longevity and fecundity between normal-type and blue-type. Field-collected blue-type males were crossed with normal-type females. The F 1 progenies from the cross were all normal-type in both male and female. The F 2 female progenies were also all normal-type but the F 2 male progenies segregated in the ratio of 1:1. The F3 progenies obtained from the cross between normal-type F 2 females and blue-type F 2 males segregated in the ratio of 3 normal-females: 3 normal-males: 1 blue-female: 1 blue-male, and those obtained from the cross between normal-type F 2 females and normal-type F 2 males segregated 4 normal-females: 3 normal-males: 1 blue-male. From these results including back crosses, it is concluded that blue-type was controlled by a single recessive gene on sex chromosome. Blue-type would be useful as the genetic marker in the population studies.
