Green(ish)bottles

There are several very similar species of greenbottle and since I didn't count the bristles on their legs, let's just say they are of the genus Lucilia.

The ivy flowers are not yet out here in Fife so there were very few insects around the ivy on this south-east facing wall.  However, these two were hanging out together and wherever the front (greener) one flew to, the more yellow one followed on behind.  It would appear to be a male chasing a female.