The Pine Webspinning Sawfly Acantholyda posticalis (Mats.) (Hymenoptera, Pamphiliidae), a Species New to Northwestern Russia

The pine webspinning sawfly Acantholyda posticalis (Mats.) (Hymenoptera, Symphyta, Pamphiliidae), a species new to Northwestern Russia, was found for the first time in St. Petersburg and Leningrad Province in 2016, 2017, and 2021. One specimen of this species from Leningrad Province was also found in the collection of the Zoological Institute of the Russian Academy of Sciences. Acantholyda posticalis is a dangerous pest of the Scots pine Pinus sylvestris, widespread in the forests of Northwestern Russia, and other pine species.