In this study, as other researches (Al-Shareef & Al-Qurashi, 2016; Grassberger et al., 2003; Queiroz, 1996; Grassberger & Reiter, 2001; Augul, 2009) we found that as the temperature increases, the length of the development is shortened. In C.albiceps, the length of larvae stage (first larval to Pupal instar) in 25°C and 30°C were 6 and 4 days, respectively. Different researchers determined different values for the length of this stage: Velez and Wolff (Velez & Wolff, 2008) (8–10 days at 25°C); Grassberger (Grassberger et al., 2003) (8–10 days); Al-Shareef and Al-Qurashi (Al-Shareef & Al-Qurashi, 2016) (6 days); Queiroz (Queiroz, 1996) (5 days at 27°C); Augul and Jassim (Augul, 2009) (3 days at 30°C); AL-Shareef and Al-Qurashi(Al-Shareef & Al-Qurashi, 2016) (5 days); Richard et al. (Richards et al., 2008) (5. 5 days); Shiravi et al.(Shiravi et al., 2011) (2–3 days at 28°C). In our research, the length of the pupal period for C.albiceps at 25°C and 30°C were determined as 5 and 3. 5 days, respectively. Again, other researchers determined different numbers: Grassberger (Grassberger et al., 2003). 1 and 5. 9 days at 25°C and 30°C, respectively; Al-Shareef and Al-Qurashi, (Al-Shareef & Al-Qurashi, 2016) 5. 5 and 4 days at 25°C and 30°C, respectively; Queiroz, (Queiroz, 1996) 4. 7 and 3 days at 27°C and 32°C respectively and Shiravi (Shiravi et al., 2011) (4–6 days at 28°C). In addition, in our study, the length of egg to adult eclosion, at 25°C and 30°C were determined as 12 and 8–8. 5 days, respectively. Other researchers got the followings: Grassberger (Grassberger et al., 2003) 13 and 9. 9 days at 25°C and 30°C; Velez and Wolff (Augul, 2009) (14 days at 25°C); Al-Shareef and Al-Qurashi, (Al-Shareef & Al-Qurashi, 2016) 11. 5 and 9 days at 25°C and 30°C respectively; Shiravi et al. (Shiravi et al., 2011) (8–12 days at 28°C); and Queiroz(Queiroz, 1996) (7 days at 32°C). The figures calculated for the life cycle of the speceis C.albiceps were more similar to the ones obtained in Al-shareef (Al-Shareef & Al-Qurashi, 2016) and Shiravi (Shiravi et al., 2011) studies and were different from others. The reason seems to be natural. As noted in various studies, inherent biogeographically variation between population (Marchenko, 1989; Donovan et al., 2006; Szpilla, 2010a; Greenberg & Kunich, 2002) food substrate (Greenberg & Kunich, 2002; Kounouz & Kamel, 2017) humidity, population density and other intrinsic factors are considered as the reason of such differences (Faria & Godoy, 2001; Rosa et al., 2006). It seems that histolysis and histogenesis of the adult organs in immature stage were the reason of the highest thermal requirement of ADD in both 25°C and 30°C, during the pupal period, and the length of this development stage has been mentioned in most researches (Al-Shareef & Al-Qurashi, 2016; Queiroz, 1996; Bharti, 2009; Defilippo et al., 2013; Donovan et al., 2006; Richards et al., 2008; Augul, 2009; Velez & Wolff, 2008). Our findings about the life cycle of C.vicina showed that this species will also have shorter life cycle as the temperature increases such a way that at 15°C, its life cycle, from the egg stage to adult, it took 32 days while at 20°C, it took 21 days. For this species, other researchers obtained similar results: Reibe et al. (Reibe et al., 2009) at 13°C and 20°C, 45 and 23 days, respectively; Defilippo et al. (Defilippo et al., 2013) at 15°C and 20°C, 30. 5 and 20 days, respectively; Bharti (Bharti, 2009) at 20°C and 25°C, 19 and 15. 29 days. The results obtained from our study were more near to the ones obtained from the study done by Defilippo et al. (Defilippo et al., 2013). In terms of rate of development in C.vicina and C.albiceps, the results of this study were compatible with the finding of the studies of Greenberg,(Greenberg, 1991) (Lowne 1890), Defillipo et al (Defilippo et al., 2013) Such a way that the length of post-feeding and pupal periods were determined one third and half the total immature development stage, respectively. The amount of ADD was calculated for C.albiceps at 25°C and 30°C respectively, as 179 and 159 which correspond to the results obtained from the study done by Shiravi et al. (Shiravi et al., 2011) the amount of ADD, at 28°C, was calculated between 130 and 195 DD. Moreover, the amount of ADD for the first larvae instar to adult of this species at 25°C and 30°C was calculated as 96°C and 110°C respectively. In the study done by AL-Shareef, (Al-Shareef & Al-Qurashi, 2016) the length of this period, at the same temperature, has been determined as 110 and 129. The life cycle of these species depends on some other factors, such as the geographic differences of population and genetics. Actually, the rate of development in necrophagous insects is the response of organisms to their thermal environment. Determining the rate of development of forensically important insects such as C.albiceps and C.vicina can give us valuable information concerning the circumstance of the death including the postmortem interval.