This photo of a very active Lasius flavus nest was taken by my wife on July 13th, 2010. Normally the mounds of this species are sealed off to the outside, but when July comes around and they sense it is high summer, the workers throw open large cavernous tunnel entrances; or more precisely, nest exits which the young winged males and females will pour out of at the right moment. 
These photos taken 25th July 2009 are of Lasius flavus virgin queens preparing for their mating flight. All photos were taken by my wife. Note the way the workers shine like amber in the sun, as the only time we see this ant specie above ground during daylight hours is either when their nests are disturbed, or when they gather for a mating flight like these are doing.
Here are 4 photos taken by my wife Jenny of Lasius flavus in their wild habitat.
The first picture shows a group of flavus workers crawling in the grass around their nest.
Photo 2 is a different shot of the same nest.
The 3rd photo is quite interesting, as it shows a Lasius flavus nest which is being shared by a colony of Myrmica rubra. Note the large number of larvae. The smaller larvae are flavus, while the larger belong to the M. rubra colony.
The last picture shows the underside of the nest roof stone. Both species of ant were harmoniously living together in peaceful co-existence, as they made no attempts to fight each other when they came into contact !