| In order to determine the number of larval instars and stadia of Stenocephus fraxini, the body length, head width, body width (3rd segment of thorax), forceps length and forceps basal width of the larva of S. fraxini were measured. According to the frequency distribution and regression analysis, the results showed that the larvae of S. fraxini had 5 instars. The head width and forceps basal width can be variable for the distinguishment of larval instars. The head width of each instars larvae were 0.414 ± 0.002, 0.526 ± 0.002, 0.713 ± 0.005, 1.003 ± 0.006 and 1.398 ± 0.010, respectively, and their forceps basal width were 0.060 ± 0.001, 0.095 ± 0.001, 0.150 ± 0.002, 0.231 ± 0.002 and 0.344 ± 0.005, respectively. The average stadia of 1-5 instar were 2.5, 3.5, 5, 8 and 40 d, respectively. The development duration of the larva of S. fraxini was about 50-70 d, with an average of 60 d. |
