Saperda inornata attacks on hybrid Populus were monitored in a stand for four years after planting. More than 60% of the whips were attacked the first year, resulting in a mean of 1.6 galls/tree (range 0-8). Branch attacks superseded stem attacks in the third and fourth years. Saperda injury significantly reduced height because of leader breakage after the second-year attacks, but the injured trees grew rapidly and recovered much of the height in the third and fourth years. Saperdas killed 4% of the trees during the study, but this was no more than would be expected in a newly established stand. Saperda, at the population levels studied, does not seem to greatly affect hybrid Populus growth or to reduce biomass.
Moore, Lincoln M. and Wilson, Louis F.
"Impact of the Poplar-Gall Saperda, Saperda Inornata (Coleoptera: Cerambycidae) on a Hybrid Populus Plantation in Michigan,"
The Great Lakes Entomologist, vol 19
Available at: https://scholar.valpo.edu/tgle/vol19/iss3/4