Hi there! Yellow jackets can be a very big problem especially for a smaller hive. They can quickly devastate a smaller or weak hive by eating brood, adult workers and honey stores. When you see any yellow jackets or hornets near your hive, or entering your hive, it is a good idea to utilize an entrance reducer. Depending on how many wasps are attacking your hive you may need to use the smallest opening to help prevent wasps from entering your hive. By using an entrance reducer you are reducing the space the guard bees will have to defend against an attacker. This can make their defense more successful.
If you are experiencing a full fledged onslaught of wasps them you may need to temporarily close your hive entrance with a piece of hardware cloth or screen. Alternatively you can cover a hive with a slightly damp sheet to help prevent a continued attack. Once you have stopped the initial attack you can use a rub like Vick's Vapor rub to help mask the smell of the hive entrance (a little goes a a long way), or utilize a robbing screen. Often if you are experiencing an intense attack leaving your hive blocked with a screen and utilize a rub for about a day or two that should stop the attack as the wasps realize they are not going to be successful and stop robbing.
I would then recommend using wasp traps in the area adjacent to your hive as a preventative measure. Also if you are feeding a hive, especially a weak hive, be aware that this increases the chances of attracting wasps or other honey bees to rob. Using feeders that sit above hive with an additional box and cover or feeders that sit inside your hive, can help lessen the risk of attracting robbers. I would avoid entrance or boardman feeder as these attract potential robbers the most. Robbing wasp species are typically at their worst during the late summer through fall. This is when honey is available to them and bee populations are decreasing for winter. It is helpful to be extra watchful of your hives during this time.
Hope this helps! Please let us know if you have any other questions about robbing or yellow jackets, we would be happy to help! You can reach out here or to our customer service line at 877-325-2221, or by email at support@beethinking.