Oriental Latrine Fly

Appearance

''C. megacephalas eggs are "oval with one flat face and another convex". Adult flies reflect a metallic blue-green color on their thorax and abdomen and have yellow gena, or cheeks. Larvae vary in size according to instar and are shaped more thickly towards the rear. ''C. megacephala'' have large red eyes, those of males being close together, and those of females farther apart. The ''cercus'' of the male is longer than that of the female.

Distribution

''Chrysomya megacephala'' has a wide geographical distribution. It is most common in the Oriental region and Australasia. It is also found in Japan and the Palearctic region. The range of ''C. megacephala'' has grown since the 1970s, with the species expanding into New Zealand and Africa, along with South, Central, and North America. ''C. megacephala'' entered the United States through harbors and airports. The fly has been found in California, as well as Texas, Louisiana, and Hawaii. ''C. megacephala'' exists in two forms, the normal and the derived. Tropical forests on the Pacific Islands, such as Samoa, are home to the normal form; the normal is considered to be the plesiomorphic form of ''C. megacephala''. The derived form is thought to have emerged from Papua New Guinea and is said to be synanthropic, or ecologically associated with humans.

Habitat

''Chrysomya megacephala'' has a wide geographical distribution. It is most common in the Oriental region and Australasia. It is also found in Japan and the Palearctic region. The range of ''C. megacephala'' has grown since the 1970s, with the species expanding into New Zealand and Africa, along with South, Central, and North America. ''C. megacephala'' entered the United States through harbors and airports. The fly has been found in California, as well as Texas, Louisiana, and Hawaii. ''C. megacephala'' exists in two forms, the normal and the derived. Tropical forests on the Pacific Islands, such as Samoa, are home to the normal form; the normal is considered to be the plesiomorphic form of ''C. megacephala''. The derived form is thought to have emerged from Papua New Guinea and is said to be synanthropic, or ecologically associated with humans.

Reproduction

The developmental stages of ''C. megacephala'' include egg, larva and pupa. A female fly may lay as many as 200 to 300 eggs, often in human feces, meat or fish. Larval stages include first, second and third instals or growth periods. The eggs take approximately one day to develop, while the larvae take 5.4 days and the pupae 5.3 days. Population numbers as well as body size are greatly influenced by temperature. The adult lifespan of the fly is approximately seven days. The development of ''C. megacephala'' is linked to the length of time spent feeding in the larval stage, as well as to temperature; the lower the temperature, the more slowly the larvae develop. In laboratory studies conducted at 27 °C., eggs hatch in 18 hours; the first molt occurs in 30 hours; the second molt in 72 hours; pupation after 144 hours; and the adult emerges after approximately 234 hours. These intervals vary depending on geographical location; other environmental factors also can determine how long flies will stay in the larval stage. Males tend to emerge two or three hours ahead of the females.

The reproduction and survival rates of ''C. megacephala'' are closely related to developmental factors, including the amount of available food, and competition from larvae of other species, such as ''C. rufifacies''. In the presence of competing larvae, those of ''C. megacephala'' spend less time feeding, leading to early pupation, smaller adults, and early reproduction. ''C. rufifacies'' is known to cannibalize maggot masses and is thus a huge competitor.''C. megacephala'' larvae are known to compete with ''C. rufifacies'' larvae for food in a mixed-species environment. Research has shown that under specific population densities, ''C. rufifacies'' will facultatively feed on other species of maggots and on its own species. When ''C. rufifacies'' and ''C. megacephala'' larvae are put into cultures separately from one another in high densities, ''C. megacephala'' has a higher rate of survival than ''C. rufifacies''. Both species had a lighter adult weight than normal and pupated earlier. The third instar of ''C. rufifacies'' will eat ''Chrysomya megacephala'' when the larvae are in high density. Despite this predation on ''Chrysomya megacephala'', both species had a lower survival rate, lighter adult weight and pupated early.In any part of the world that uses organophosphates, ''C. megacephala'' could prove to be beneficial. Organophosphate compounds are used in agriculture and are highly toxic. Organophosphate poisoning often causes death, and in many cases, by evaluating the body tissue and fluids, the toxin can be identified as the source of the poisoning. However, it is somewhat difficult to evaluate the body tissue in a body that is exceedingly decomposed. Nevertheless, a medical examiner in Hawaii worked on a case in which poisoning by malathion, an organophosphate insecticide, was thought to be the cause of death. The victim’s stomach contents and body fat were examined and found to have contained malathion. The fly larvae of ''Chrysomya megacephala'' and ''Chrysomya rufifacies'' were also present at the scene on the body and were tested for malathion. Both of these species did contain malathion, but there had been no previous record of organophosphates in their larvae. Studying larvae from decomposed remains may provide an effective method of determining the presence of these toxins in a body that is extremely decayed.

Predators

''Chrysomya albiceps'' is also known to prey on ''C. megacephala'' during the larval stage when they must compete for the same food source. Beetles are also known to prey on ''C. megacephala''. ''C. megacephala'' is not predaceous in the adult or larval form, preferring to feed on necrophagous material of any kind, such as fish, cows and humans.