Flesh flies and houseflies may look similar, but key differences in their behaviour mean the methods to control them are somewhat different. Flesh flies may look superficially like houseflies, but if you attempt to deal with a flesh fly...
Flesh flies and houseflies may look similar, but key differences in their behaviour mean the methods to control them are somewhat different.
Flesh flies may look superficially like houseflies, but if you attempt to deal with a flesh fly problem assuming you’re dealing with houseflies, you may experience the dreaded callback!
When it comes to the appearance of the adult flies, they may look similar at a glance, especially when flying around a room, but placed side by side, flesh flies are normally quite a lot larger than houseflies with subtle differences in colouration. There are some 150 species of flesh fly in Australia (not all identified), so the identifying features and description of their behaviour in this article are somewhat generalised.
One of the key behavioural differences between the housefly and the flesh flies is their choice of substrate for laying eggs. Houseflies will lay their eggs on decaying organic matter such as food waste, carrion and faeces. Flesh flies will lay their eggs around garbage, manure and decaying organic matter, but they commonly breed on carrion and the open wounds of mammals (from which they get their name). This last point is critical in dealing with a flesh fly problem – if the problem is occurring inside a building it is likely that there is a dead creature in the roof, ceiling, walls or subfloor, such as a rodent, bird or possum. Locating and removing the dead animal is vital in achieving control.
Flesh flies will often lay their maggots on fresh carcasses – check the source of infestation for indoor flesh fly problems
The key life cycle difference between the housefly and flesh flies is that the housefly lays eggs, whereas flesh flies are ovoviviparous. This means they deposit live maggots or maggots that are about to hatch (depending on species) directly on their preferred substrate. This means flesh flies can quite exploit any suitable breeding site and complete their life cycle a little bit quicker than the housefly.
Housefly adults prefer sugary materials such as rotting fruit and vegetables, although female houseflies also seek out sources of protein (for egg laying). Flesh fly adults feed on liquid foods from a variety of sources including sugary substances such as nectar and fruit juices. Interestingly, such nectars are not only sugar-based but are also high in amino acids.
Flesh fly, Sarcophagaspp., showing three stripes on the thorax and chequerboard abdomen
Flesh fly (Sarcophaga spp.)
Body length: Up to 20 mm (varies by species)
Thorax: Grey with three black stripes
Abdomen: Grey/black chequered pattern
Wings: Translucent
Eyes: Red
The housefly, Musca domestica, showing four stripes on the thorax
Housefly (Musca domestica)
Body length: 5-7mm long
Thorax: Grey with four black stripes
Abdomen: Grey or yellowish with a dark midline stripe. Can have irregular dark patches on the sides of the abdomen
Wings: Translucent. There is a sharp upward bend on the fourth longitudinal wing vein
Eyes: Reddish
Elimination of breeding sites outside the home is essential for management of both houseflies and flesh flies. This primarily means keeping garbage in sealed bins well away from buildings and removing any faeces (animal droppings and manure for gardens). For flesh fly problems that originate inside buildings, the location of the animal carcass where the larvae are developing is important. Note that the larvae will only develop on moist carcasses; once a carcass has dried out it is no longer a suitable development site.
Apart from identifying the source of infestation, much of the same control techniques can be used for both houseflies and flesh flies – sticky traps, light traps, insecticide spraying or the use of fly baits around garbage areas, and insecticide spraying of fly resting sites. For indoor fly problems, residual insecticide treatments should be targeted at windowsills and the corners of windows, as flies are readily attracted to the light.
As always, it’s essential to take time to make the correct identification and a complete a thorough inspection to identify the source of infestation before developing a suitable management plan.