Relative reduction in growth of root and shoot systems of the woody plant,Euonymus fortunei(Turcz) Hand.-Mazz., caused by the euonymus scale,Unaspis euonymi(Comstock) (Homoptera: Diaspididae), was determined, and the distribution and development of scales on the plants were investigated at the end of one generation. Weight of total abscised leaves increased, whereas weight and area of intact leaves, stem weight, and plant height decreased with increasing scale density. Root weight was not affected by scale infestation, but the root/shoot ratio increased with increasing density of scales. More females than males settled on the stems, whereas the sex ratio was nearly equal on the leaves. The proportion of scales reaching maturity was higher for females on stems than on leaves, and higher for males on leaves than on stems. This indicated either differential mortality or slower development of the sexes, depending upon settling site.