Tiny Flies in garden

My garden is overrun by tiny flies. They come out in the morning and the evening for about 2 - 3 hours.
They dont bite but get in everything. They seem to be coming out of the neighbours lelandi trees.
What are they? and Is there anything i can do to reduce the number of these?
I'll spray the trees if i have to but with what ?

"My garden is overrun by tiny flies.".... just wait until they grow up - then the trouble will start

Have they got big (in proportion to their bodies) red eyes?
http://www.pestproducts.com/fruitflyimage.htm#Fruit%20Fly%20Picture

Is there a compost heap nearby?

They might be fruit flies. I've managed to create a massive fruit-fly mother planet in my compost bin. I'm hoping they don't evolve and create their own military-industrial complex anytime soon.


BraveInca

The past few evenings I have had these also. They sort of stay in gangs/swarms in different parts of the garden.

I ran through one lot with a spade wafting them away but they still stayed in same place after I stopped ... weird.

They do however always seem to be under the canopy of leylandii trees but not all along..