Yellow jackets in fall
The yellow jackets in this video are fighting over a dead bee. These scavenger/predators are about 6 inches below the entrance to a honey bee colony.
It is fall, a time of year when food sources for yellow jackets begin to diminish. The yellow jackets do not forage far from their colony, maybe 50 feet. They seek prey near the ground. Beekeepers tend to put their honey bee colonies in groups of 3 to 60 or more. They set the colonies on stands usually four inches above the ground. These practices are great for yellow jackets. Several colonies close together increases odors, a sweet scent of honey that guides the wasps. Colony entrances close to the ground make access for these predators easy.
From experience I find that it may not always be the weaker colonies that succumb to yellow jacket predation. The wide entrance close to the ground is an easy target. When many wasps come and get inside the bee colony the bees can become despondent. If this happens the colony will probably be killed. The honey bee has not met this predator before the late 19th century and have not developed good defense mechanisms to repel many such invaders.
It can be a frustrating time for beekeepers in NW Oregon and other areas where dry falls and healthy yellow jacket populations abound. Options for protecting your bees include: moving colonies, a difficult task that is not always possible; finding and collecting the yellow jacket nest, a task that is time consuming and requires careful preparation; increasing the height and reducing the nest entrance (best option in my opinion). An entrance 16 inches above the ground seems to confuse the invaders and a reduced entrance give the bees less area to defend.