Nocturnal Oviposition Behavior of Blow Flies (Diptera: Calliphoridae) BERNARD GREENBERG Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60680
J. Med. Entomol. 27(5): 807-810 (1990) ABSTRACT It is widely held that blow flies, in general, and Phoenicia sericata (Meigen), in particular, are not active at night and do not lay eggs during that time. P. sericata is thought to require sunlight and warmth for oviposition. Three common and forensically important flies—Calliphora vicina (Robineau-Desvoidy), P. sericata, and Phormia regina (Meigen)—oviposited during the dark hours of the night during the summers of 1988 and 1989. Nocturnal oviposition can alter the usual estimate of the postmortem interval in homicide cases by as much as 12 h. Cases are presented that serve to change our concept of P. sericata from an obligate heliophile to a facultative heliophile that has a willingness to enter dim or dark places to oviposit. KEY WORDS
Insecta, blow flies, nocturnal oviposition, forensic entomology
by fly biologists that blow flies out-of-doors are not active and do not oviposit at night (Greenberg 1985). Typical diurnal activity curves show little movement toward bait in early daylight, a peak toward early afternoon, and a sharp decline in activity toward late afternoon (Nuorteva 1959; Baumgartner & Greenberg 1984, 1985). In summer and in the tropics, this seems to be linked to light because the temperature can be 25°C and the weather perfect for flying. Cessation of oviposition at night is of forensic importance because it could change an estimate of the postmortem interval by as much as 12 h. Nuorteva (1977) sums up current belief as follows: "Forensically, it is important to note that sarcosaprophagous . . . Calliphoridae . . . fly only during daytime. Thus, if eggs are detected in a corpse during the night or early morning, the conclusion can be reached that death occurred during the previous day or earlier" (see also Smith 1986). Another widely accepted view with forensic significance is that the oviposition behavior of Phaenicia sericata (Meigen) approaches obligate heliophily. Thus we find statements that P. sericata usually oviposits between 1100 and 1400 hours at maximum sunshine (Hall 1948), and it does not normally oviposit on carcasses with a surface temperature below 30°C (Cragg 1956, cited by Smith [1986]). And again: "It is also known that, in temperate areas, adult female P. sericata will only lay their eggs upon sunlit carcasses during late morning and early afternoon hours. P. sericata females require a high surface temperature (+85°F) in order to receive the proper egg releasing stimuli."1 ReferIT IS GENERALLY ACKNOWLEDGED
1 W. D. Lord, Testimony in the trial, State of Connecticut vs. Erich Seebeck/Adam John, 18 July 1986; New London, Conn.; pp. 53, 62, 69, 70, 73.
ring to this species, Nuorteva (1977) concludes: "Therefore, if eggs of this species are found on a human corpse lying on a place that is in shadow during the entire day, the finding may be interpreted as indicating that the corpse has been removed from an area that was sunnier earlier." Clearly, this view has received wide currency among forensic entomologists and there is no way of knowing how frequently it may have influenced estimates of the postmortem interval in homicide cases (Greenberg 1988). Contrary evidence is presented by Smeeton et al. (1984), who recorded eggs of P. sericata on 18 of 20 human corpses found indoors (not necessarily in the sun) in Aukland, New Zealand. Green (1951) noted that small numbers of gravid female blow flies penetrated into dimly lit hanging or chilling rooms in an English slaughterhouse for the purpose of laying eggs. Although P. sericata was the dominant blowfly in the slaughterhouse environment, Green did not specify the fly species, nor did he say that they actually laid eggs. This paper presents evidence of nocturnal oviposition by three species of forensically important blow flies—P. sericata, Phormia regina (Meigen), and Calliphora vicina (Robineau-Desvoidy)—and observations on the oviposition behavior of P. sericata, based on homicide cases and experiments, that are contrary to the generally accepted view. Materials and Methods Decapitated, skinned, frozen carcasses of laboratory rats were thawed, transported in Ziploc plastic bags, and set out at different times of night in a garden in a residential suburb on the southside of Chicago in June, July, and August 1988. The experiment was repeated in 1989 at a similar res-
0022-2585/90/0807-0810$02.00/0 © 1990 Entomological Society of America
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Vol. 27, no. 5
JOURNAL OF MEDICAL ENTOMOLOGY
Table 1. Summer nocturnal oviposition on carrion by several species of blowflies Species
Date
Time, hours (CST)
Calliphora vicina C. vicina Phormia regina Phoenicia sericata P. sericata P. sericata
27 June 1988 27 June 1988 14 July 1988 1 Aug. 1988 27 July 1989 28 July 1989
0100-0400 0100-0400 0100-0400 0100-0400 1200-0300 1200-0300
idential site not far away; this time, ground beef was the bait. At both sites, the gardens faced an unpaved alley lit by sodium vapor lamps. Bait was placed in an empty rat cage on the ground under the alley light or under a bush away from the light. Temperature and relative humidity were measured with a Taylor sling psychrometer, Arden, N.C., and light intensity was measured with a Gossen Luna-Pro light meter, Federal Republic of Germany, pointed at the bait. All measurements were made about 30 cm from the bait. After exposure, each bait was immediately placed in a separate Ziploc bag with wood shavings; the opening of the bag was pressed shut and sealed with tape. Minute pinholes were made for air, and the bags were returned to the laboratory where they were placed in empty fly cages (made of nylon screen, 12 mesh/ cm) at room temperature and observed for 1-2 mo for presence of fly stages before they were discarded as negative. Where oviposition had occurred, adults eclosed within the bag and were counted after they died. No stray flies, which could account for spurious ovipositions, were ever observed in the fly cages. In 1988, baits were exposed as follows: (1) twice in shade under a bush at sunset ±0.5 hours (21 June, 34.5°C, 46% RH, 175 lux; and 14 July, 28°C, 68% RH, 88 lux); (2) four times in shade under a bush during the first week of June, 2100-2200 hours (CDST), and four times under the same bush, 22002400 hours (sunset at approximately 2030 hours, 26-30.5°C, 66-76% RH, 4 lux at 2100-2200 hours and 3 lux at 2200-2400 hours); (3) eleven times, June-August, under an alley light or in shade under a bush, 0100-0400 hours. In 1989, baits were exposed on six nights, 12000300 hours, July and August, under an alley light and in the shade of a bush. Results Oviposition by P. sericata occurred on both rat carcasses set out in shade for about 1 h at sunset; 152 adults were bred from the carcass used on 21 June and 61 adults from the carcass used on 14 July 1988. No oviposition occurred on the eight carcasses set out from 2100 to 2200 hours and from 2200 to 2400 hours during the first week of June 1988. There were four ovipositions in 11 trials on carcasses set out from 0100 to 0400 hours between 27
Temp, °C 20 20 17 24 24
23.5
RH, %
Lux
No. adults reared
70 70 40 40 100 87
0.7 0.5 0.5 0.5 0.4 0.2
20 1 8 10 203 53
June and 24 August 1988; data are summarized in Table 1. The three species of ovipositing flies were C. vicina, P. sericata, and P. regina. The latter two species oviposited in the shade of a bush; C. vicina oviposited under the dim light in the alley. In every case, the number of eggs was small. In 1989, there were two ovipositions in six trials on bait set out 1200-0300 hours. Only P. sericata was involved, and the number of eggs was much larger on the bait under the bush than in the alley; both numbers greatly exceeded nighttime figures for 1988 (Table 1). Discussion Three species of forensically important flies oviposited during the darkest hours of the night, under dim light provided by an alley light, and in the deep shade of a bush. Ovipositions occurred in approximately 33% of the trials in both years. Whether the output is relatively small as in 1988, or approximately normal as in 1989, the forensic entomologist must reckon with the possibility of nocturnal oviposition in his calculation of the postmortem interval. Because determination of the postmortem interval is based on the oldest specimens (and these could be from a nocturnal oviposition), there could be as much as a 12-h difference in the estimate of postmortem interval if oviposition actually occurred at 2100 hours instead of an assumed time of 0900 hours the next day. The neighborhoods in which these experiments were conducted are made up of typical suburban single-family dwellings with tree-lined streets and gardens. Homes are not equipped with garbage disposers, and garbage is picked up once a week from the alley. This ambience maintains a resident population of blowflies, particularly of P. sericata and P. regina, from May through September. Calliphora vicina is generally reported to be a cool-weather fly throughout its distribution (Greenberg 1973). Sychevskaia (1965) confirmed the data of Smirnov (1940), which showed that the ovaries of this species become inactive during the hot summer months, and inhibition ceases toward the end of August. It is noteworthy that the summer of 1988 was the hottest (and driest) on record in the Midwest, with more than 40 d above 32°C in the Chicago area. C. vicina not only was present in July under these conditions but was active at night and laid fertile eggs, albeit a few.
September 1990
GREENBERG: NOCTURNAL OVIPOSITION OF BLOW FLIES
Phaenicia sericata often is the most common urban blow fly and is frequently used as a forensic indicator. As we have seen, there are numerous references to this fly's requirement of warmth and sunlight for oviposition despite the fact that the fly is routinely reared in the laboratory under artificial light and well below the reputed threshold of 30°C (Cragg 1956), and it can cause myiasis in hospital settings (Greenberg 1984). The following four cases provide additional insights into the oviposition behavior of this fly and others with which it is sometimes associated in human cadavers. Two Bodies in a Car Trunk. Two bodies were discovered near Chicago, 8 May 1981, when a car trunk was pried open. On the bodies and elsewhere in the trunk were postfeeding larvae of P. sericata, various larval instars of P. regina, and pupae of Muscina assimilis (Fallen). All car doors and windows were shut and the presumed entry of the flies into the dark trunk was through the drainage hole in the spare tire well. Ambient temperature reached 26.5°C once (and then only for 1 h in May) during the entire spring that the bodies were in the trunk. The Mafia Case. Two Mafia hit men were found in the closed trunk of a Volvo in a Chicago suburb on 15 July 1983. All car windows and doors were shut. Second and third instars of P. sericata, P. regina, and Cochliomyia macellaria (F.) were recovered from the bodies. Larvae on one body were about a day older than those on the other body, raising the possibility that one had been killed a day earlier than the other. The weather was hot during the relevant period, with air temperature reaching the mid-30s (°C). Temperature reached 46°C in the trunk when measurements were made a few days later when weather conditions were similar. Girl on the Bathroom Floor. The partially decomposed body of a 9-yr-old girl was found on a tiled bathroom floor on the ground level of a boarded-up, abandoned building in Waukegan, 111., on 19 June 1984. The boarded-up bathroom window faced a dimly lit light shaft and with the door closed (as it was when the victim was found), the room was completely dark. Oviposition by three species of blow flies had occurred in this room. There were numerous dead and live teneral adults of P. sericata and P. regina in the apartment, and various instars of their larvae were on the body; in addition, a large number of C. vicina pupae were on the bathroom floor, none of which had yet eclosed. Average outdoor temperatures during the relevant period ranged from 19 to 26°C, but the temperature of the apartment and particularly the bathroom fluctuated little and remained near the low end. A Double Murder. The bodies of a man and woman, both infested with third instars of P. sericata, were discovered in a house in a Chicago suburb on 20 July 1986. Doors and windows were shut, an air conditioner was running, and the temperature was 24°C. The woman's body was on a couch in the living room. The man's body, more heavily
809
infested, was on the bedroom floor. The bedroom had two windows facing east and north, and with the curtains drawn and the shades pulled down, the light was subdued. Not only was sunlight excluded in each of the above situations, but the temperature was well below the presumed threshold for oviposition. Phaenicia sericata is widely distributed and polymorphic in some of its behavior: in Great Britain it is a primary myiasis fly; in North America it is not. Possibly, in Europe, its oviposition behavior is more constrained by temperature and light than we have found, although this is unlikely. In any event, there is an urgent need for accurate information on the details of blow fly biology as a basis for valid entomological input in forensic cases. Acknowledgment I thank Julia Harris and Judith Jean-Baptiste for excellent technical assistance. References Cited Baumgartner, D. L. & B. Greenberg. 1984. The genus Chrysomya (Diptera: Calliphoridae) in the New World. J. Med. Entomol. 21: 105-113. 1985. Distribution and medical ecology of the blow flies (Diptera: Calliphoridae) of Peru. Ann. Entomol. Soc. Am. 78: 565-587. Cragg, J. B. 1956. The olfactory behavior of Lucilia species (Diptera) under natural conditions. Ann. Appl. Biol. 44: 467-477. Green, A. A. 1951. Blowflies in slaughterhouses. J. R. Sanit. Inst. 71: 138-145. Greenberg, B. 1973. Flies and disease, vol. 2. Biology and disease transmission. Princeton University Press, Princeton, N.J. 1984. Two cases of human myiasis caused by Phaenicia sericata (Diptera: Calliphoridae) in Chicago area hospitals. J. Med. Entomol. 21: 615. 1985. Forensic entomology: case studies. Bull. Entomol. Soc. Am. 31: 25-28. 1988. A manual of forensic entomology by K. G. F. Smith, 1986. Cornell University Press, Ithaca, N.Y. (book review). J. N.Y. Entomol. Soc. 96: 489-491. Hall, D. G. 1948. The blowflies of North America. Thomas Say Foundation, vol. IV. Entomological Society of America, College Park, Md. Nuorteva, P. 1959. Studies on the significance of flies in the transmission of poliomyelitis. III. The composition of the blow fly fauna and the activity of the flies in relation to the weather during the epidemic season of poliomyelitis in South Finland. Ann. Entomol. Fenn. 25: 121-136. 1977. Sarcosaprophagous insects as forensic indicators, vol. 2, pp. 1072-1095. In C. G. Tedeschi, W. G. Eckert & L. G. Tedeschi [eds.], Forensic medicine: a study in trauma and environmental hazards. Saunders, Philadelphia. Smeeton, W. M. I., T. D. Koelmeyer, B. A. Holloway & P. Singh. 1984. Insects associated with exposed human corpses in Aukland, New Zealand. Med. Sci. Law 24: 167-174. Smirnov, E. S. 1940. Le probleme des mouches a Tadjikistane. Med. Parasitol. 9: 515-517.
810
JOURNAL OF MEDICAL ENTOMOLOGY
Smith, K. G. V. 1986. A manual of forensic entomology. British Museum (Natural History), London, and Cornell University Press, Ithaca, N.Y. Sychevskaia, V. I. 1965. Biology and ecology of Calliphora tncina R.-D. in central Asia. Zool. Zhurn. 44: 552-560 (in Russian).
Vol. 27, no. 5
Received for publication 20 December 1989; accepted 24 January 1990.
J. Med. Entomol. 27(5): 807-810 (1990) ABSTRACT It is widely held that blow flies, in general, and Phoenicia sericata (Meigen), in particular, are not active at night and do not lay eggs during that time. P. sericata is thought to require sunlight and warmth for oviposition. Three common and forensically important flies—Calliphora vicina (Robineau-Desvoidy), P. sericata, and Phormia regina (Meigen)—oviposited during the dark hours of the night during the summers of 1988 and 1989. Nocturnal oviposition can alter the usual estimate of the postmortem interval in homicide cases by as much as 12 h. Cases are presented that serve to change our concept of P. sericata from an obligate heliophile to a facultative heliophile that has a willingness to enter dim or dark places to oviposit. KEY WORDS
Insecta, blow flies, nocturnal oviposition, forensic entomology
by fly biologists that blow flies out-of-doors are not active and do not oviposit at night (Greenberg 1985). Typical diurnal activity curves show little movement toward bait in early daylight, a peak toward early afternoon, and a sharp decline in activity toward late afternoon (Nuorteva 1959; Baumgartner & Greenberg 1984, 1985). In summer and in the tropics, this seems to be linked to light because the temperature can be 25°C and the weather perfect for flying. Cessation of oviposition at night is of forensic importance because it could change an estimate of the postmortem interval by as much as 12 h. Nuorteva (1977) sums up current belief as follows: "Forensically, it is important to note that sarcosaprophagous . . . Calliphoridae . . . fly only during daytime. Thus, if eggs are detected in a corpse during the night or early morning, the conclusion can be reached that death occurred during the previous day or earlier" (see also Smith 1986). Another widely accepted view with forensic significance is that the oviposition behavior of Phaenicia sericata (Meigen) approaches obligate heliophily. Thus we find statements that P. sericata usually oviposits between 1100 and 1400 hours at maximum sunshine (Hall 1948), and it does not normally oviposit on carcasses with a surface temperature below 30°C (Cragg 1956, cited by Smith [1986]). And again: "It is also known that, in temperate areas, adult female P. sericata will only lay their eggs upon sunlit carcasses during late morning and early afternoon hours. P. sericata females require a high surface temperature (+85°F) in order to receive the proper egg releasing stimuli."1 ReferIT IS GENERALLY ACKNOWLEDGED
1 W. D. Lord, Testimony in the trial, State of Connecticut vs. Erich Seebeck/Adam John, 18 July 1986; New London, Conn.; pp. 53, 62, 69, 70, 73.
ring to this species, Nuorteva (1977) concludes: "Therefore, if eggs of this species are found on a human corpse lying on a place that is in shadow during the entire day, the finding may be interpreted as indicating that the corpse has been removed from an area that was sunnier earlier." Clearly, this view has received wide currency among forensic entomologists and there is no way of knowing how frequently it may have influenced estimates of the postmortem interval in homicide cases (Greenberg 1988). Contrary evidence is presented by Smeeton et al. (1984), who recorded eggs of P. sericata on 18 of 20 human corpses found indoors (not necessarily in the sun) in Aukland, New Zealand. Green (1951) noted that small numbers of gravid female blow flies penetrated into dimly lit hanging or chilling rooms in an English slaughterhouse for the purpose of laying eggs. Although P. sericata was the dominant blowfly in the slaughterhouse environment, Green did not specify the fly species, nor did he say that they actually laid eggs. This paper presents evidence of nocturnal oviposition by three species of forensically important blow flies—P. sericata, Phormia regina (Meigen), and Calliphora vicina (Robineau-Desvoidy)—and observations on the oviposition behavior of P. sericata, based on homicide cases and experiments, that are contrary to the generally accepted view. Materials and Methods Decapitated, skinned, frozen carcasses of laboratory rats were thawed, transported in Ziploc plastic bags, and set out at different times of night in a garden in a residential suburb on the southside of Chicago in June, July, and August 1988. The experiment was repeated in 1989 at a similar res-
0022-2585/90/0807-0810$02.00/0 © 1990 Entomological Society of America
808
Vol. 27, no. 5
JOURNAL OF MEDICAL ENTOMOLOGY
Table 1. Summer nocturnal oviposition on carrion by several species of blowflies Species
Date
Time, hours (CST)
Calliphora vicina C. vicina Phormia regina Phoenicia sericata P. sericata P. sericata
27 June 1988 27 June 1988 14 July 1988 1 Aug. 1988 27 July 1989 28 July 1989
0100-0400 0100-0400 0100-0400 0100-0400 1200-0300 1200-0300
idential site not far away; this time, ground beef was the bait. At both sites, the gardens faced an unpaved alley lit by sodium vapor lamps. Bait was placed in an empty rat cage on the ground under the alley light or under a bush away from the light. Temperature and relative humidity were measured with a Taylor sling psychrometer, Arden, N.C., and light intensity was measured with a Gossen Luna-Pro light meter, Federal Republic of Germany, pointed at the bait. All measurements were made about 30 cm from the bait. After exposure, each bait was immediately placed in a separate Ziploc bag with wood shavings; the opening of the bag was pressed shut and sealed with tape. Minute pinholes were made for air, and the bags were returned to the laboratory where they were placed in empty fly cages (made of nylon screen, 12 mesh/ cm) at room temperature and observed for 1-2 mo for presence of fly stages before they were discarded as negative. Where oviposition had occurred, adults eclosed within the bag and were counted after they died. No stray flies, which could account for spurious ovipositions, were ever observed in the fly cages. In 1988, baits were exposed as follows: (1) twice in shade under a bush at sunset ±0.5 hours (21 June, 34.5°C, 46% RH, 175 lux; and 14 July, 28°C, 68% RH, 88 lux); (2) four times in shade under a bush during the first week of June, 2100-2200 hours (CDST), and four times under the same bush, 22002400 hours (sunset at approximately 2030 hours, 26-30.5°C, 66-76% RH, 4 lux at 2100-2200 hours and 3 lux at 2200-2400 hours); (3) eleven times, June-August, under an alley light or in shade under a bush, 0100-0400 hours. In 1989, baits were exposed on six nights, 12000300 hours, July and August, under an alley light and in the shade of a bush. Results Oviposition by P. sericata occurred on both rat carcasses set out in shade for about 1 h at sunset; 152 adults were bred from the carcass used on 21 June and 61 adults from the carcass used on 14 July 1988. No oviposition occurred on the eight carcasses set out from 2100 to 2200 hours and from 2200 to 2400 hours during the first week of June 1988. There were four ovipositions in 11 trials on carcasses set out from 0100 to 0400 hours between 27
Temp, °C 20 20 17 24 24
23.5
RH, %
Lux
No. adults reared
70 70 40 40 100 87
0.7 0.5 0.5 0.5 0.4 0.2
20 1 8 10 203 53
June and 24 August 1988; data are summarized in Table 1. The three species of ovipositing flies were C. vicina, P. sericata, and P. regina. The latter two species oviposited in the shade of a bush; C. vicina oviposited under the dim light in the alley. In every case, the number of eggs was small. In 1989, there were two ovipositions in six trials on bait set out 1200-0300 hours. Only P. sericata was involved, and the number of eggs was much larger on the bait under the bush than in the alley; both numbers greatly exceeded nighttime figures for 1988 (Table 1). Discussion Three species of forensically important flies oviposited during the darkest hours of the night, under dim light provided by an alley light, and in the deep shade of a bush. Ovipositions occurred in approximately 33% of the trials in both years. Whether the output is relatively small as in 1988, or approximately normal as in 1989, the forensic entomologist must reckon with the possibility of nocturnal oviposition in his calculation of the postmortem interval. Because determination of the postmortem interval is based on the oldest specimens (and these could be from a nocturnal oviposition), there could be as much as a 12-h difference in the estimate of postmortem interval if oviposition actually occurred at 2100 hours instead of an assumed time of 0900 hours the next day. The neighborhoods in which these experiments were conducted are made up of typical suburban single-family dwellings with tree-lined streets and gardens. Homes are not equipped with garbage disposers, and garbage is picked up once a week from the alley. This ambience maintains a resident population of blowflies, particularly of P. sericata and P. regina, from May through September. Calliphora vicina is generally reported to be a cool-weather fly throughout its distribution (Greenberg 1973). Sychevskaia (1965) confirmed the data of Smirnov (1940), which showed that the ovaries of this species become inactive during the hot summer months, and inhibition ceases toward the end of August. It is noteworthy that the summer of 1988 was the hottest (and driest) on record in the Midwest, with more than 40 d above 32°C in the Chicago area. C. vicina not only was present in July under these conditions but was active at night and laid fertile eggs, albeit a few.
September 1990
GREENBERG: NOCTURNAL OVIPOSITION OF BLOW FLIES
Phaenicia sericata often is the most common urban blow fly and is frequently used as a forensic indicator. As we have seen, there are numerous references to this fly's requirement of warmth and sunlight for oviposition despite the fact that the fly is routinely reared in the laboratory under artificial light and well below the reputed threshold of 30°C (Cragg 1956), and it can cause myiasis in hospital settings (Greenberg 1984). The following four cases provide additional insights into the oviposition behavior of this fly and others with which it is sometimes associated in human cadavers. Two Bodies in a Car Trunk. Two bodies were discovered near Chicago, 8 May 1981, when a car trunk was pried open. On the bodies and elsewhere in the trunk were postfeeding larvae of P. sericata, various larval instars of P. regina, and pupae of Muscina assimilis (Fallen). All car doors and windows were shut and the presumed entry of the flies into the dark trunk was through the drainage hole in the spare tire well. Ambient temperature reached 26.5°C once (and then only for 1 h in May) during the entire spring that the bodies were in the trunk. The Mafia Case. Two Mafia hit men were found in the closed trunk of a Volvo in a Chicago suburb on 15 July 1983. All car windows and doors were shut. Second and third instars of P. sericata, P. regina, and Cochliomyia macellaria (F.) were recovered from the bodies. Larvae on one body were about a day older than those on the other body, raising the possibility that one had been killed a day earlier than the other. The weather was hot during the relevant period, with air temperature reaching the mid-30s (°C). Temperature reached 46°C in the trunk when measurements were made a few days later when weather conditions were similar. Girl on the Bathroom Floor. The partially decomposed body of a 9-yr-old girl was found on a tiled bathroom floor on the ground level of a boarded-up, abandoned building in Waukegan, 111., on 19 June 1984. The boarded-up bathroom window faced a dimly lit light shaft and with the door closed (as it was when the victim was found), the room was completely dark. Oviposition by three species of blow flies had occurred in this room. There were numerous dead and live teneral adults of P. sericata and P. regina in the apartment, and various instars of their larvae were on the body; in addition, a large number of C. vicina pupae were on the bathroom floor, none of which had yet eclosed. Average outdoor temperatures during the relevant period ranged from 19 to 26°C, but the temperature of the apartment and particularly the bathroom fluctuated little and remained near the low end. A Double Murder. The bodies of a man and woman, both infested with third instars of P. sericata, were discovered in a house in a Chicago suburb on 20 July 1986. Doors and windows were shut, an air conditioner was running, and the temperature was 24°C. The woman's body was on a couch in the living room. The man's body, more heavily
809
infested, was on the bedroom floor. The bedroom had two windows facing east and north, and with the curtains drawn and the shades pulled down, the light was subdued. Not only was sunlight excluded in each of the above situations, but the temperature was well below the presumed threshold for oviposition. Phaenicia sericata is widely distributed and polymorphic in some of its behavior: in Great Britain it is a primary myiasis fly; in North America it is not. Possibly, in Europe, its oviposition behavior is more constrained by temperature and light than we have found, although this is unlikely. In any event, there is an urgent need for accurate information on the details of blow fly biology as a basis for valid entomological input in forensic cases. Acknowledgment I thank Julia Harris and Judith Jean-Baptiste for excellent technical assistance. References Cited Baumgartner, D. L. & B. Greenberg. 1984. The genus Chrysomya (Diptera: Calliphoridae) in the New World. J. Med. Entomol. 21: 105-113. 1985. Distribution and medical ecology of the blow flies (Diptera: Calliphoridae) of Peru. Ann. Entomol. Soc. Am. 78: 565-587. Cragg, J. B. 1956. The olfactory behavior of Lucilia species (Diptera) under natural conditions. Ann. Appl. Biol. 44: 467-477. Green, A. A. 1951. Blowflies in slaughterhouses. J. R. Sanit. Inst. 71: 138-145. Greenberg, B. 1973. Flies and disease, vol. 2. Biology and disease transmission. Princeton University Press, Princeton, N.J. 1984. Two cases of human myiasis caused by Phaenicia sericata (Diptera: Calliphoridae) in Chicago area hospitals. J. Med. Entomol. 21: 615. 1985. Forensic entomology: case studies. Bull. Entomol. Soc. Am. 31: 25-28. 1988. A manual of forensic entomology by K. G. F. Smith, 1986. Cornell University Press, Ithaca, N.Y. (book review). J. N.Y. Entomol. Soc. 96: 489-491. Hall, D. G. 1948. The blowflies of North America. Thomas Say Foundation, vol. IV. Entomological Society of America, College Park, Md. Nuorteva, P. 1959. Studies on the significance of flies in the transmission of poliomyelitis. III. The composition of the blow fly fauna and the activity of the flies in relation to the weather during the epidemic season of poliomyelitis in South Finland. Ann. Entomol. Fenn. 25: 121-136. 1977. Sarcosaprophagous insects as forensic indicators, vol. 2, pp. 1072-1095. In C. G. Tedeschi, W. G. Eckert & L. G. Tedeschi [eds.], Forensic medicine: a study in trauma and environmental hazards. Saunders, Philadelphia. Smeeton, W. M. I., T. D. Koelmeyer, B. A. Holloway & P. Singh. 1984. Insects associated with exposed human corpses in Aukland, New Zealand. Med. Sci. Law 24: 167-174. Smirnov, E. S. 1940. Le probleme des mouches a Tadjikistane. Med. Parasitol. 9: 515-517.
810
JOURNAL OF MEDICAL ENTOMOLOGY
Smith, K. G. V. 1986. A manual of forensic entomology. British Museum (Natural History), London, and Cornell University Press, Ithaca, N.Y. Sychevskaia, V. I. 1965. Biology and ecology of Calliphora tncina R.-D. in central Asia. Zool. Zhurn. 44: 552-560 (in Russian).
Vol. 27, no. 5
Received for publication 20 December 1989; accepted 24 January 1990.
