Abstract: Shoot boring noctu ids are the most importan t pests in bamboo shoot periods. In th is paper, insectpopulat ion b iology theory w as used to ana lyze quantitatively the niches of three dom inant shoo t boring noctu ids.These noctuids w ere investigated on three bamboo spec ies, Phy llostachy s praecox, P. iridescins and P. glauca,respectively. Itw as found that the popu lation density ofK umasia kumaso and Apamea ap am eoides w ere the ma inspec ies. The former reached the peak from late A pr il to early M ay, exper ienc ing seven days or so, and the latteraggregated on m id M ay, lasting about ten days. These tw o spec ies occurred separately. Oligia vulgaris w erecaptured few er in the field and observed to be less infested than the prev iousmentioned tw o species. Analysis fromeco log ica l ind ices show ed that temporal n ich breadth ofK. kumaso w as the narrow est among three noctu ids. Thetempora l n iche sim ilarity be tw een Oligia vulgaris and Apamea kumaso w as h igher than 0. 7 w hile the interspec ificcompetition coefficient w as 0. 907 3. The results ind icated tha t the competition betw een O. vulgaris andK. kumasoeventua lly resoulted in the sign if icantly h igher populat ion density ofK. kumaso than O. vulgaris. The temporaln iche breath ra lues ofK. kumaso and A. apam eoides w as very sim ilar. It had never observed that three spec iescoex isted on the same shoots. The coex istence rat ios of tw o o f them w as only 0. 97%.