Although wasps do a good job eating up other insects most of the time they can be a nuisance to a beehive and sometimes may rob a hive so thoroughly that the bees starve during the winter. Wasps occasionally remove bee brood as food also.
DEFENDING THE HIVE
If wasps are seen entering and leaving a beehive they are almost certainly robbing. Unfortunately the wasps are better armed with sting and strong jaws than the bees and are also faster moving, so they can dodge the guard bees and gain entry.
To reduce this problem inspect your hive and make sure there are no small gaps or holes where wasps can enter between the boxes or where there is damage. Restrict the entrance by putting in a wood block so that the bees only have about a 4cm wide entrance to defend at the most.
Despite these precautions andd hoovering up about half a gallon of wasps with my bee vacuum device, still the wasps robbed two strong colonies in National hives to destruction during September. Strangely, two skeps of bees standing next to the hives were not affected and their bees successfully defended their property. Why would that be?
The simplest wasp trap is a 2litre plastic bottle with a couple of round holes snipped in it with a pair of scissors. Make the holes about 2cm diameter on opposite sides about halfway up the bottle. Put a small amount of water in the bottle and add something to attract the wasps - beer does a good job and does not interest bees. Rotting fruit also works well. Hang the trap nearby in the open. Leave the bottle cap on.
Beware, however, that your trap also works at night and you may accidentally kill off moths if you leave it out after dark.
If the wasps gain entry to a hive, you can catch and remove those that got in so they never come back. Cut two 2litre plastic bottles. Cut off the bottom from one so it is full width at the bottom edge. Now take the top part from the other bottle to make a funnel shape which fits inside the base of bottle one. You now have a way in at the base and a closed bottle to accumulate the wasps. Stick the two together by putting a strip of Gaffer tape all round the joint.
This trap sits on the top board , roof removed , and covers the feed hole. Make sure it sits down neatly with no gaps.
Wasps enter the hive from below, go up into the upper part and cannot find any way out except into your trap. Bees seldom show any interest in entering the bottles so they almost all avoid being caught .
When the trap has a lot of wasps in it, I remove it and suck out the wasps with my vacuum device (described on the www.BedfordshireBeekeepers.org.uk ' website), but dropping it into a bowl of soapy water will do a quick job of despatching the wasps. Pour out the contents into the compost heap, rinse and re-set.