ORIGINAL ARTICLE Nocturnal oviposition behavior of blowflies (Diptera: Calliphoridae) in the southern hemisphere (South Africa and Australia) and its forensic implications Kirstin A. Williams 1,2 & James F. Wallman 3 & Bryan D. Lessard 3 & Christopher R. J. Kavazos 3 & D. Nkosinathi Mazungula 1 & Martin H. Villet 1 Accepted: 27 February 2017 # Springer Science+Business Media New York 2017 Abstract Published research has offered contradictory evi- dence of the occurrence of nocturnal oviposition by carrion- breeding blowflies, a behavior that can affect the interpretation of forensic estimates of a minimum post mortem interval ( min PMI) by up to 12 hours, depending on latitude and season. The majority of published studies are from the northern hemi- sphere. Field experiments were conducted in South Africa and Australia that extend observations to species of the southern hemisphere. Various vertebrate carrion was exposed at night in summer under different lunar phases and/or artificial light- ing, and in woodland and pasture areas. Three laboratory ex- periments were also conducted. No nocturnal oviposition oc- curred outdoors in Berry, Australia, but Lucilia cuprina, Lucilia sericata and Chrysomya megacephala laid eggs outdoors at night in Grahamstown and Durban, South Africa. In laboratory experiments L. sericata, L. cuprina, Chrysomya chloropyga and Chrysomya putoria laid eggs and Calliphora augur depos- ited larvae under nocturnal conditions. Chrysomya albiceps and C. chloropyga laid eggs in darkness with increasing likeli- hood as ambient temperature increased. This study shows that nocturnal ovi/larviposition by carrion-breeding blowflies is possible in both South Africa and Australia. The forensic issue is therefore not whether nocturnal oviposition occurs, but rather whether the conditions of a particular case are more or less conducive to it. Circadian rhythms and physiological thresh- olds (particularly temperature and humidity) appear to act indi- vidually and in conjunction to stimulate or inhibit nocturnal laying. The significance of carcass size, freezing and handling of carcasses and comprehensive quantification for experimental design is discussed, and recommendations are made for future laboratory and case scene experiments. Keywords Blowflies . Flesh flies . Forensic entomology . Circadian rhythms . Minimum post mortem interval Introduction The minimum time since death, or minimum post-mortem interval ( min PMI), of a body can be estimated from the devel- opmental stage of certain carrion-breeding insects associated with it [1–3] by identifying the oldest immature stages present on the body, estimating their age as indicated by their state of development [4, 5] and taking environmental conditions into account to work backwards to estimate the date when the eggs or larvae were deposited. While diurnal oviposition is well known in carrion flies, there is considerable debate regarding the incidence of noctur- nal oviposition. The question of whether blowflies lay eggs at night has been raised at least twice in hearings of criminal cases [6, 7]. An assumption by a forensic entomologist of nocturnal inactivity of flies, and thus a lack of confidence in a night-time min PMI, could affect such estimates by up to 12 hours, depending on latitude and season. This is particularly pertinent because many deaths occur at night [8]. Such uncer- tainty is undesirable since ill-formulated interpretations of the min PMI could potentially lead to miscarriages of justice. * Kirstin A. Williams kirstin.williams@durban.gov.za 1 Southern African Forensic Entomology Research Laboratory, Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa 2 Entomology Department, Durban Natural Science Museum, Durban, South Africa 3 Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia Forensic Sci Med Pathol DOI 10.1007/s12024-017-9861-x