By measuring the width of head capsules and rearing observation in laboratory, the results showed that there were 4 instars in larval stage of the kapok long-horned borer, Glenea cantor (Fabricius). The average idths of head capsule from 1 to 4 instars were (0.66±0.20), (1.45±0.20), (2.22±0.22) and (3.26±0.29) mm, respectively. The linear formula of larval instars (Y) and width of head capsule of larvae (X) was: Y=0.2975+1.1606X. At 25℃, the average stadia of the 1st instar to the 4th instar were (5.25±0.60), (4.94±0.58), (5.98±0.63)d and (22.92±1.28)d, respectively, and the total larval duration was (39.09±2.14)d. The larval morphology were also described.