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This is the first study in Brazil that monitored the nocturnal oviposition behavior of Chrysomya putoria, a species of forensic importance, in order to verify if individuals of this species oviposit at night. Groups of 10 flies (5 male and 5 female) distributed in ten cages were kept in a fume hood and submitted to total darkness or exposed to artificial light for eleven consecutive hours through four experimental conditions in the laboratory. Two verifications were made to see if the females oviposited in the offered substrate of about 20 g of chicken gizzard per cage. Verification 1 occurred at 09:00 pm in the evening experiments and at 09:00 am in the daytime experiments. Verification 2 occurred at 05:00 am in the night experiments and at 05:00 pm in the daytime experiments. Each experiment lasted 5 d. C. putorialaid eggs at night (with or without light) and the quantity of eggs was significantly similar to those produced during the day under natural light or in total darkness. Only the amount of eggs produced during the day in the absence of light was considerably greater than in the typical daytime period. The females oviposited in greater quantity in the nights when the average temperature was between 23 and 24.8°C and relative humidity above 81%. Ovipositions only occurred at temperatures above 21°C and humidity above 56% during the day. Finally, it is necessary that more evaluations on the effect of variables on blowfly behavior are performed to better understand nocturnal oviposition.

Chrysomya megacephala(Fab. 1794) (Diptera: Calliphoridae) is a very important species for forensic entomology, mainly contributing estimations of the postmortem interval (PMI) in judicial investigations. There are some doubts about the nocturnal oviposition of these flies, which could lead to errors in the PMI calculation. This study aimed to monitor the nocturnal oviposition behavior of this species through four experimental conditions carried out in laboratory. Ten cages, each containing five males and females (n= 100), were kept in a fume hood and subjected to total darkness or to artificial light for 11 consecutive hours. Two verifications were performed to determine whether the females deposited eggs on the substrate of ~20 g of chicken gizzards per cage. The first verification occurred at 9:00 pm in nocturnal experiments and at 09:00 am in diurnal experiments. The second verification occurred at 05:00 am in nocturnal experiments and at 05:00 pm in diurnal experiments. Each experiment lasted 5 d. Chrysomya megacephaladeposited eggs at night under artificial light and in total darkness, but the amount of eggs was significantly lower when compared with the daytime experiments in dark conditions and under natural light. Oviposition occurred when the average temperature was around 25°C (± 2°C) and relative humidity around 73% (± 6%). Night oviposition is a possibility which should not be ruled out. Thus, future experiments are recommended.