Monday, April 4, 2011

Golden Dung Fly

This pretty yellow fly is called the Golden Dung Fly (Scathophaga stercoraria), they are also called the Yellow Dung Fly. While it is true that they are pretty, they hang out in very unsavory places, namely piles of cow dung. They measure up to 3/8 of an inch in length, males are bright golden-yellow with orange-yellow fur on the front legs. Females are a little duller in color with green-brown tinges. They also lack the bright fur on the front legs.

These flies are predators and feed on a wide variety of insects. Those that are found on flowers are not after nectar, they are after the insects that are after the nectar. Those that are found on piles of dung, are feeding on the blow flies and other insects that are gathered on the dung. Females gather at the dung piles to feed and to deposit eggs on the surface of the poo. They will lay their eggs in the small hills of the dung, avoiding points and depressions as these areas dry out more quickly. Moisture is needed to insure the survival of the eggs and the larvae.  Depressions may also store excess water after rainfall and would drown the flies offspring, so it is key to their survival that the female lay her eggs exactly where they need to be. When the eggs hatch the maggots are also predatory and will feed on small insects found in the dung. In about 20 days, give or take a few days depending on the weather conditions, they will fall to the ground and pupate. In several days to a couple weeks the adults will emerge. They are capable of having up to five generations per year depending on their location and the weather.

Many things feed on these flies, including birds, insects and bats. Robber flies are particularly fond of these flies.
These flies are even susceptible to sexually transmitted diseases that are commonly spread by mites or fungi. This causes sterility in the fly or can outwardly kill the fly. In either case it has a detrimental affect on the ability of this fly to reproduce.

This is the first I've ever spotted this fly, now I am prompted to seek out the cow patties on our farm to further investigate what species beside the typical blow flies are using the cow piles as either a food source or an incubator for their eggs.

1 comment:

  1. A lot of species visit that patty, I will look forward to see what all you find.