This'll fix your picnic.
Super glue a hook to the flat top and tie it up. Screw on a pop bottle with some wasp bait inside and there ya go!
Inspiration and trap information credits to Derek Zoli.
Check this out - mistertech's remix Wasp Trap has several improvements which you may prefer.
The opening is a tad small for wasps. Might work or not. Shorten it if you like by splitting in Netfabb Basic. This was my first attempt before the Deluxe Wasp Traps.