Lateral view

Ch. megacephala habitus

Comparison of ommatidia in Chrysomya saffranea (left) and Chrysomya megacephala (right)

Australian distribution

Taxonomy

Family: Calliphoridae

Subfamily: Chrysomyinae

Genus: Chrysomya Robineau Desvoidy 1830

Species: megacephala (Fabricius 1794)

 

The first-instar larva was described by Sukontason et al. (2003) and Szpila et al. (2013). The second-instar larva was described by Erzinçlioglu (1984) and Sukontason et al. (2003), the third-instar larva by Holloway (1991), Erzinçlioglu (1984) and Sukontason et al. (2003).

Biology

Chrysomya megacephala is one of the most common members of the genus in Australia. It is a large species, often exceeding 10mm in length and is of tropical origin. It has been reported in forensic cases in Thailand, and in other developing countries, and has been responsible for causing myiasis in humans (Sukontason et al. 2005). Because it is readily attracted to garbage, it can also act as a vector of disease, and is therefore also of sanitary importance. Adults breed mostly in carrion, but they are also attracted to garbage and faeces. It has been bred by J. F. Wallman from human corpses in News South Wales and Queensland.

Larval development of Ch. megacephala has been investigated by O’Flynn (1983), Sukontason et al. (2008), Wells and Kurahashi (1994) and Wijesundara (1957). The species prefers the warmer months, and will completely disappear from some areas during winter. During summer, it may be the most abundant carrion-breeding blowfly in certain parts of its range.

It is morphologically similar to its sister species, Chrysomya saffranea, but can be distinguished by its black supravibrissal and subvibrissal setulae. Chrysomya megacephala and Ch. saffranea males have eyes with enlarged ommatidia in the upper two-thirds, however in Ch. megacephala the upper two-thirds are sharply demarcated from the smaller ones in the lower third, whereas they are not sharply demarcated in Ch. saffranea (see picture). To determine the gender of your fly click here.

Distribution

This species is found across northern Australia and also occurs commonly in south-east Asia. In Australia, it has been recorded from the Australian Capital Territory, New South Wales, Northern Territory, Queensland, South Australia and Western Australia.

Relevant Literature

Erzinçlioglu, Y.Z. (1984) Studies on the morphology and taxonomy of the immature stages of Calliphoridae, with analysis of phylogenetic relationships within the family, and between it and other groups in the Cyclorrhapha (Diptera). Ph.D., University of Durham.

Holloway, B.A. (1991) Identification of third-instar larvae of flystrike and carrion-associated blowflies in New Zealand (Diptera: Calliphoridae). New Zealand Entomologist 14, 24-28.

Kurahashi, H. (1987) The blow flies of New Guinea, Bismark Archipelago and Bougainville Island (Diptera: Calliphoridae), Tokyo, The Entomological Society of Japan.

O'Flynn, M.A. (1983) The succession and rate of development of blowflies in southern Queensland and the application of these data to forensic entomology. Journal of the Australian Entomological Society 22, 137-148.

Sukontason, K.L., Narongchai, P., Sripakdee, D., Boonchu, N., Chaiwong, T., Ngern-Klun, R., Piangjai, S. and Sukontason, K. (2005) First report of human Myiasis caused by Chrysomya megacephala and Chrysomya rufifacies (Diptera: Calliphoridae) in Thailand, and its implications in forensic entomology. Journal of Medical Entomology 42, 702-704.

Sukontason, K., Piangjai, S., Siriwattanarungsee, S. and Sukontason, K.L. (2008) Morphology and developmental rate of blowflies Chrysomya megacephala and Chrysomya rufifacies in Thailand: application in forensic entomology. Parasitology Research 102, 1207-1216.

Szpila, K., Hall, M.J., Sukontason, K. and Tantawi, T. I. (2013) Morphology and identification of first instars of the European and Mediterranean blowflies of forensic importance. Part I: Chrysomyinae. Medical and veterinary Entomology 27, 181-193.

Wells, J.D. and Kurahashi, H. (1994) Chrysomya megacephala (Fabricus) (Diptera: Calliphoridae) development: rate, variation and the implications for forensic entomology. Japanese Journal of Sanitary Zoology 45, 303-309.

Wijesundara, D.P. (1957) The life history and bionomics of Chrysomyia megacephala (Fab.). Ceylon Journal of Science 25, 169-185.