When visiting the garden today I discovered it was swarming with hundreds of wasps. Wasps seem to come and go in my garden at various times of the year but when they're around it's not such a pleasant place to be. However, while wasps can be a nuisance, they do apparently provide a much needed service in the garden. I found the following paragraph on this site here: http://eartheasy.com/live_natwasp_control.htm
Wasps, although annoying, should be thought of as beneficial insects.
They prey mainly on other insects, many of which are pests. In general, they avoid human activity and should only be considered a nuisance when nesting near homes or high traffic areas.
Hopefully this will mean an end to the green stinky bug that's been ravaging my cabbages and other leafy greens lately. That's not to say I want the wasps sticking around for too long at least not in such big numbers. The above mentioned site also had a few instructions for making a wasp trap so I thought I'd try making one and see what happens.
Using a water bottle, I cut the top off it, put some water with a bit of dishwashing soap in it, then smeared some jam 'round the neck of the bottle. Then I turned the neck part upside down and stuck it back in the bottle and sealed it with a couple of bits of tape. I also added some yellow paper around the top of it to help attract the wasps.
I guess it's just a case of waiting now to see what happens, but there's still plenty of wasps around where I left the trap. Apparently if you catch a queen the wasps will relocate elsewhere.