[Objectives]  To understand what induces larvae of Brithys crini Fabricius to play dead. [Methods]  The effects of internal and external factors on the frequency and the duration of playing dead were observed. [Results]  (1) The duration of feigned death increased with larval body weight but this trend was not statistically significant. (2) Duration decreased significantly with the number of repeated stimuli. The duration from the 1^st to the 10^th stimulus (85.6 s) was longer than that from the 11^th to the 20^th stimulus (67.3 s). (3) The duration of feigned death following mechanical stimulation of 2, 5 and 10 Newtons (N) (82.3, 97.4 and 78.3 s, respectively)was shorter than that after receiving a stimulus of 6 N (157.0 s). The relationship between duration and applied force could be described by a parabolic equation. (4) The duration  following exposure to the sound of wind (65.6 s) was shorter than that following exposure to bird and frog calls (144.8 s and 134.1 s, respectively). (5) There was a significant difference in duration following exposure to different LED sources. Durations of feigned death following red flashing, red, yellow, green, white and blue LED treatments were 54.7, 64.3, 82.7, 90.6, 96.9 and 112.3 s, respectively. The difference in the frequency of feigned death was insignificant among all treatments. [Conclusion]  The larvae of B. crini are induced to play dead by both internal and external factors.