- Price, P. W.
Five clones of the willow, Salix exigua Nuttall, along the Weber River, Utah, produced shorter shoots with increasing ramet age. The number of ovipositions by the shoot-galling sawfly, Euura exiguae Smith, correlated positively with shoot length, so that sawfly density was high on younger ramets of a clone and low on older ramets. The sawfly attacked the most vigorous parts of the clones. Survival of progeny in galls decreased with ramet age from 60% survival on 1-yr-old ramets to 26% survival on 6-yr-old ramets when plant-induced mortality was considered alone. The effects of parasitoids on the pattern of sawfly attack was not significant.