Abstract: To investigate the impacts of feeding materials on the adult life span of Monochamus alternatus, major vector of the fatal disease PWN, adult pine sawyers were reared with four kinds of feeding materials, namely mixed twigs, current year twig, two year old twig and three year old twig in Xiangshan, Zhejiang Province in 2001 Results showed that the Japanese pine sawyer fed with mixed twigs got the longest average life span When reared with non selective twigs, the average life span shortened sharply with age of feeding twigs The changes of life span were highly related with the feeding behaviors Calculated as per beetle, current year twig got the largest feeding volume, which was remarkably bigger than those of two year twig and three year twig Calculated as per beetle per day, current year twig also got the biggest figure and remarkably larger than those of two year twig and three year twig However, feeding volume of mixed twigs was not remarkably different with any of the single year old twigs, which meant that when fed with single year old twig, the pine sawyer increased its feeding volume Feeding volumes of different year old twigs in the mixed twigs rearing showed that current year twig was the dominant feeding materials.