Characteristic: Wings with a small round discal cell. On the scutellum, there often are some spines. (So it gots its name "soldier fly") There are no bristles on the body. Like the hover flies the soldier flies resemble bees or wasps.

Chloromyia formosa  male

Chloromyia formosa  female

This is a male. Not only because the eyes, but also because the shiny yellow gold abdomen. Females have a metallic bluegreen abdomen. The legs are black with yellow knees.
It's a beautiful fly.
Length 7-9 mm, April-August.
The larvae live in damp soil, compost and leaf litter and they feed on decaying vegetable matter.

Two photos of a Chloromyia formosa female        

It has two spots on its face.

This is a male. A male has an orange spot on its abdomen.
The abdomen of the females are entirely greenish brown.
Length to 16 mm. 
The larvae live in manure.
In September I oft have these beautiful flies in the garden.

Dark green. The abdomen is black.

I have photgaphed this Beris chalybata on April 30 
This fly was about 10 mm

Beris chalybata  (subfamily Beris)

A characteristic of the genus Beris are the six spines on the scutellum. They have a slim body.

Another similar member of the family is the Beris morrisii, but this fly flies later in the year.

Photo 6-5-2010 Beris chalybata male. The hind legs are thick. (near the feet) 

        If you look closely, you see the spines on the scutellum.

Microchrysa polita     

The adult of this soldier fly is small and bright metallic green. The male has red eyes
March - September
Length 4-6 mm
Larvae in organic matter, compost heaps

Length: about 10 mm.

This small, blacksoldier fly I saw in June 2009 on the goldenrod.
It is to identify by the wings. The first half is dark.
The male has dark antennae. The female has light antennae.

Larva: Under the bark, in decaying wood and leaf waste.

Information waarneming.nl. (Han thanks for determination)

Female.

  Photo 27-6-2010