How do wasps know the date?

Now that September has arrived, everything has a very Autumnal feel; the leaves are beginning to turn, the fields are harvested and the starlings are gathering for the outward journey. They line up on the heavy power wires as if waiting for a train. I watched three of them mobbing a sparrow-hawk (I think) yesterday morning. He didn't wait around. The villagers have taken the best of the blackberries, but the apples are still growing to be harvested later in the Autumn.

One of the villagers shows me his haul.

He said he was going home to make apple and blackberry crumble. Mmmmm...

In the field opposite, which used to ba part of an orchard, the damsons have let me down. Rather like my plum trees, there was a glut last year and they're having a rest this year.

Damson bushes, devoid of fruit - perhaps next year.

However, my main point was how do the wasps, who have plagued us for a month now, know that the last day of August has gone and so should they?

The wasp trap - with wasps.

We had a very well-mannered young man come and cut back the laurel hedge so we can now see the thatched cottage behind and it lets much more light in, which should help the plants around the plum tree. I'll try to find time for a picture later. Anyway, i wasn't at home while he did the job so, last evening, I rang him up to say thankyou for doing such a good job. I think he was in the middle of his evening meal, so I felt rather embarrassed - silly, isn't it?