I was around my grandmas house yesterday and noticed hundreds of Lasius niger workers running all over the patio in some sort of craze. It took me a while to realise where they were all coming from but when I found the main nest entrance (in the gap between the house and the first patio paving stone) there were lots of winged males pouring out. I kept on checking throughout the day yesterday and today but as of yet no queens, just loads of males. The mating flights are nigh!
From now on, is the time to watch them like a Hawk They are extremely busy here too! The entrance holes are as wide as possible, which is a sign of heightened activity.
Over the last few days in the warmth, there has been winged males pouring out of the entrance holes here too. On our car park there are several niger nests (we are predominantly nigers around here) and what worried me the other evening, somebody had parked their car so that their wheels where nearly in the nest entrances. They might have run over quite a few of the alates already
Flights usually take place late afternoon, when the wind has dropped and it becomes very humid. I think it needs to warm up more in the UK, as we have had a lot of rain and gale force winds here lately.