What's in a name?--Blowflies and Selangor
by T.G. Goh
The etymology of the name of the Selangor state has been lost to time. But one of the many hypotheses proposed is that it is derived from the Malay word selangau which means 'a blowfly'. Blowflies, or langau in Malay, can be differentiated from other flies, which in Malay are called lalat, by their large, reddish eyes and metallic bodies.
Unlike houseflies that tend to prefer decomposing vegetation or fruit, blowflies are very well-adapted to feeding on carrion and occasionally dung. Some species will even lay their eggs onto living animals, of which the maggots cut through the skin and develop as parasites inside the body. A single female blowfly can lay hundreds of eggs at one time. These clumps of eggs are called 'blows' and the English name 'blowfly' originates from that term.
Upon emerging from their eggs, typical blowfly maggots gather together into writhing balls. This is a strategy to lower the amount of heat and enzymes that would be lost if they didn't co-operate. As maggot development is closely linked to heat, the maggot masses which reach up to 50 °C can rapidly accelerate the growth of the maggots. Additionally, the enzymes secreted by these flies produce noxious ammonia compounds that prevent other insects from colonising the carcass.
The maggots gorge themselves on the carcass until they grow three times their original size before they crawl away from the carcass to find dry leaves or sand in which they pupate. If the food supply runs out before they reach pupation, they are known to cannibalise each other. The entire process takes less than a month, after which the adults emerge and start their desperately competitive life cycle all over again.
Adult flies spend most of their time preparing to breed by feeding on foods which are high in protein and sugar. This is one of thee reasons why they are attracted to toilets and cafeterias, as human food and dung is just as nutritious to them. In some cases dung is preferred because it is easier to detect through smell.
While blowflies tend to use their sense of smell to detect food, the males are believed to use their vision to find females. In some species, the eyes of male blowflies have evolved to cover almost the entire head except the mouth area. This gives male blowflies a field of vision similar to a fish-eye lens while it perches on saplings and leaves and watches for females.
The fly pictured above is a male Chrysomya megacephala, which means 'Giant-headed Colorful Fly' in Latin. With an oversized head and flashy but terribly vulgar appearance, it may be fitting after all that the richest state in Malaysia is named after a creature of voracious consumption.
T.G. Goh is an entomologist based in the Museum of Zoology. He can frequently be seen walking around campus, ruminating on the state of biodiversity; it is from his shortcuts through untarred territories that he gets the inspiration for his columns. You can contact him at u_loji@yahoo.com.
