The Beekeeper’s Companion Since 1861
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Honey Bee Biology

Small Hive Beetle Behavior with Movie Clips

- June 1, 2015 - Dr. Wyatt A. Mangum - (excerpt)

With summer approaching, the hotter temperatures bring on the beetles, small hive beetles. Beekeepers need to be aware of small hive beetles, especially if the pests are endemic in their local areas. In my location of Piedmont Virginia, I regard small hive beetles as more of a problem than the greater wax moths. Quite often the beetles will out compete the wax moths for unprotected comb in weak colonies.

Let’s begin by reviewing how to identify adult small hive beetles. Usually the adult beetles are black in color. Typically with a strong colony covering its combs, small hive beetles are found in the upper corners of the hive. The worker bees keep the adult beetles corralled off the comb (see Figure 1) or restricted to the edges of the comb in empty cells, well away from the brood nest unless something is wrong. The adult beetles can be found corralled into other places like corners of the bottom board (assuming an all wood floor). In these situations, usually the adult beetles can manage only a very low rate of reproduction.

However, once the beekeeper disturbs the colony, the bees restricting the small hive beetle movement leave their post and the beetles escape. Small hive beetles flee from the light and hide in open cells and recesses as shown in Figure 2. After the hive inspection, a strong colony can corral its beetles again.

The adult beetles vary slightly in size, which probably depends on the food availability when they were larvae. Roughly, their small size is less than one-third the size of a worker bee. That beetle size makes them small enough to pass through the screen of a package-bee shipping crate. Furthermore, small hive beetles easily pass through the wire of a screen-floor hive (bottom board), which is eight mesh holes per inch. Understand that screen floor hives opening directly to the ground are completely open to small hive beetles.

Upon finding beetles for the first time, the beekeeper might need to collect specimens to confirm their identification. Picking up small hive beetles is not as easy as one might think. Even when dry (no slime), the back of the beetle’s shell seems slippery. Sometimes when I hold a beetle between my fingers, it still manages to slip out. Not only does their small size make them awkward to pick up, their curved body shape makes them difficult to grasp. The beetle’s body shape is almost like an upside-down dish. In addition, the beetle can withdraw its legs under its body for protection, not leaving much for even a bee to grasp. When observed from this close-up perspective, it is no wonder why bees have such difficulty evicting these pests, hence the corralling behavior, a sort of stalemate (see Figure 3).
The beetle’s antennae are typically retracted under its head, protecting them from damage, particularly from biting bees. If the beetle extends its antennae, one can see small knobs on their ends. These are called “clubbed” antennae. (More specifically, small hive beetle antennae are called capitate because the terminal segments enlarge abruptly.) This clubbed antennal structure is considerably different from the honey bee antennae, which are straight, lacking any hint of a terminal enlargement. (Honey bee antennae are called geniculate, meaning with a long first segment, an elbow turn, followed by several small segments as a cylindrical shaft.)

The two different antennal structures, along with the beetles apparently restricted in their corrals for days, make the answer to this next question quite astounding: How do the small hive beetles feed when corralled? The beetles are not in contact with any stored food, no cells of nectar or honey. They do not need it – because the bees are feeding the small hive beetles. Yes, that is right. The bees feed the beetles.

In my bee house that holds 30 glass observation hives,..