Biological characteristics of a new record pest insect Acanthocinus carinulatus Gebler has been reported in China. During the last few years, outbreaks of this insect in larch (Larix gmelinii Rupr.) plantations of Aershan, Inner Mongolia have occurred. Each year one generation is born. The insects only damage the phloem in L. gmelinii, overwinter in galleries as larvae and pupate in May of the following year. The pupation culminates in late May. The pupal phase lasts about 45 d. Adults emerge in early June and require nutrition after emergence. Mating and oviposition occur from late June to early August and the adult males and females and may copulate many times in their lifetime. The female adults lay eggs in bark crevices. Oviposition sites with one egg occupy 70.5% of all sites, sites with three eggs occupy 6.8% and 22.7% of all crevices are without eggs. Eggs stay in this stage for a period of 7 to 11 d.Larvae hatch in early July and hibernate in early September. The rate of successful hatching is only 37.8%.