Wasps can be a problem in the apiary
The common wasp (Vespula vulgaris), or "yellow jackets" as they are called in the U.S.A., can be a problem towards the end of the season. They are opportunists and are much tougher than bees. They fly at lower temperatures and on a one-to-one basis will win a battle with a honey bee.
There are a large number of wasp species, the vast majority of which are solitary. Common wasps are social and that helps cause the problem for beekeepers. In the early spring and summer, worker wasps are looking for protein to feed the brood. Much of the protein comes from insects, such as aphids, which is why wasps are seen as beneficial. The workers need a high energy sugary diet, which comes from fruit, nectar and a sugary substance that is exuded by the larvae. Towards the end of the summer when there are less larvae to feed, worker wasps switch to other sources, so they seek out weak beehives.
The colony cycle of common wasps is different to honey bees. Queen wasps hibernate during the winter and start the nest on their own in the spring. When there are workers to take over, they stay in the nest laying eggs. Towards the end of the summer queens and drones are produced. They mate and queens seek hibernation for the winter. The nest declines and dies out following a few hard frosts.
Depending on the temperature and the part of the country, wasps are usually gone by November, occasionally into December, or that is the case in West Sussex. To show how things vary, but to cut a long story short, on 2nd January 2014 I saw a colony of a neighbouring beekeeper being robbed out by wasps. A week later one of mine was robbed out too! This is obviously exceptional but it may show a trend.
As with bees robbing, prevention is better than cure, so the relevant precautions suggested for bees applies to wasps.
It might make the beekeeper feel more comfortable to put out wasp traps and you may appear to trap a lot, but quite frankly I think you are wasting your time. There are far more wasp nests than you think and in killing a few individuals you aren't even scratching the surface.