[Aim]  To clarify differences in the 24-hour activity profiles and timing of oviposition in three darkling beetle species, Anatolica hammarstromi, Pterocoma loczyi, and Platyscelis obovatus, from the Xinjiang, thereby providing information useful for timing the collection of adult specimens and eggs. [Methods]  Under controlled environmental conditions of (30 ± 0.5) ℃, 30% ± 6% relative humidity, and a photoperiod of 16 L∶8 D, the number of active and ovipositing adults of each species were recorded hourly for an entire day over a 5 d period. [Results]  Adult A. hammarstromi and P. loczyi were predominantly diurnal. 78.70% of A. hammarstromi were active during the day compared to 21.30% at night, with peak activity occurring at 13∶58. 90.92% of all eggs laid were laid during daylight hours with the peak of oviposition occurred at 14∶46. 69.12% of P. loczyi were active during the day and 30.88% at night, with peak activity observed at 15∶50. Approximately 75.41% of the eggs of this species were laid during the day with the peak of oviposition occurring at 17∶33. In contrast, just 43.27% of P. obovatus were active during the day compared to 56.73% at night, with peak activity occurring at 3∶35. Just 37.55% of the eggs of this species were laid during the day compared to 62.45% at night, with the peak of oviposition occurring at 00∶14. [Conclusion]  All three species of darkling beetle had significantly different, closely synchronized, circadian rhythms in both oviposition and locomotor activity. A. hammarstromi and P. loczyi were both predominantly diurnal in both locomotor activity and oviposition, with 81.88% (P < 0.000 1) of A. hammarstromi and 74.59% of P. loczyi (P < 0.000 1) active during the day. 92.08% (P = 0.000 7) of the eggs of A. hammarstromi and 83.68% of the eggs of P. loczyi (P = 0.011 5) were laid during the day. In contrast, P. obovatus was mainly nocturnal, with 56.73% (P < 0.000 1) of adults active during the night and 62.45% (P = 0.000 7), of oviposition occurring at night.