can anyone help me identify a black flying insect?

Question

2 -4cm in length, black metalic shiny, in group of 50 or more, didnt appear aggressive, very quick moving(flying), were around in Dec/Jan, Western Suburbs, Sydney, NSW, were very interested in my apple tree and garden.

Answer 1

Well, here is a link with some different Australian flies.

http://www.geocities.com/brisbane_flies/index.html

Here are a couple that might fit the bill. Go thru the site and see if you can find something that is close. Flies are almost as diverse as beetles.

http://www.geocities.com/brisbane_flies/STRATIOMYIDAE.htm

http://www.geocities.com/brisbane_flies/DOLICHOPODIDAE.htm

http://www.geocities.com/brisbane_flies/SYRPHIDAE.htm