Abstract: This paper describes a new species of Tenthredinidae, which is a serious pest of the maple Acer truncatum Bge in Taishan Mountain, Shandong Province. The type specimens are deposited in the collection of forest insects in the Forest Research Institute, the Chinese Academy of Forestry.Messa acericola n. sp.Female Head reddish yellow, shining; apices of mandibles black; palpi yellowish brown; apices of first and second antennae reddish yellow, the rest segments black; eyes black. Thorax piceous; posterior angles of pronotum, regulae yellowish brown; juneture of prescutum and scutum reddish yellow; wings translucent; veins black; pterostigma pale yellow(fig. 1—2); legs yellowish brown. Abdomen piceous; central part of terga 1 with a yellowish white band; lancet see fig. 1—1. Posterior part of prescutum and abdominal terga with very rare and fine punctuations. Anterior margin of clypeus straight; posterior tentorial pits very deep; median fovea round and deep; transversal suture and lateral sutures distinct and deep; coronal suture indistinct; median ocellar basin rather deep. OOL: POL: OCL=5:4.5:4.Body length 3.7mm; antennae 9 segments; 8th segment:9th segment=0.07:0.14. Male unknownHost Acer truncatum BgeHolotype ♀, Taian County, Shandong Province (Taishan mountain), 1990. 6. 14, Liu Jing leg., 300-800m. Paratypes 10 ♀♀, Same as Holotype.The species resambles Mess glaucopis(Konow), but differs from the latter by the following characters: 9th antennal segment is more than one and a half times as long as 8th; hind femur is completely yellowish brown; antenna except for the first segment and apex of the second segment is black; the host is the maple Acer truncatum.

Key words: Hymenoptera, Symphyta, Tenthredinidae