By sucking sap from the young twigs of the hemlock tree, tree growth is retarded by the woolly adelgid, causing needles to change color from deep green to grayish green and to drop prematurely.

通过吮吸铁杉幼嫩枝的汁液，树木的生长被毛茸茸的叶蝉阻碍，导致针叶从深绿色变为灰绿色，并提早掉落。