Nymphal growth and reproduction of the predatory bug Picromerus bidens were studied in laboratory under constant temperature (+23 degrees C, +1 degrees C) and two constant photoperiods (long day LD 20:4 and short day SD 12:12). It was found no differences in nymphal growth. All females of the SD variant began oviposition in 16,4 + 2,33 days after adult mout. Reproduction continued up to death of females (about In a month since their emergence). Females of LD delayed oviposition. Only 2 or 21 females layed eggs before the end of the experiment (35th day of adult life). The LD delay of oviposition is considered as an aestivation (summer diapause or oligopause). Probably, in nature early females enter aestivation in the beginning of summer and begin oviposition in August-September when days become shorter. Later females begin reproduction without any delay.