The Beekeeper’s Companion Since 1861
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Beekeeping Basics

How to Be Inhospitable to Unwanted Hive Guests: Small Hive Beetle Management for Any Time of Year

- January 1, 2024 - Eleanor Schumacher - (excerpt)

small hive beetle

Why should we talk about small hive beetles in January? Wouldn’t it be more fun to talk about this Super El Niño and parse out the many fun beekeeping tasks we can accomplish on a mild, sunny day? Well, sure, you can keep pretending SHB isn’t a major concern. But your bees can’t — because SHB are still out there, lurking now in your clusters!

Yes, SHB have a high winter mortality rate, and many of them are falling from the cluster and dying cold, hungry deaths on your bottom boards. But not all of them. Some of them are safely stowed away in comb cells with your bees and will be there to greet you this spring, ready to race your colonies in a population contest and cause chaos and disorder wherever they can.

Small hive beetles are pests with a pesky reputation. We like not thinking about them but I think we tolerate them more than we should. Science has not loudly identified them as significant disease vectors or as a negative influence on overwintering success, but there do exist solid studies that link SHB to the spread of bee pathogens, from deformed wing virus to American foulbrood. For this and a host of other reasons we’ll consider, we should make it a higher priority to limit SHB populations in our apiaries.

Most beekeepers proactively manage for SHB by keeping strong, disease-free hives situated in full sun with good queens laying solid patterns. Optimal conditions like these help colonies defend themselves against beetles without too much trouble. But queens get old, and sunny apiaries get shady as trees get bigger. Things in nature never stay the same and beekeepers have to be on the ready to cut beetles off at the pass.

This was brought home for me when I discovered a problem hive in my “shady apiary.” I never wanted to keep bees in the shade, but when my cousin told me 10 years ago that he wanted to “help the bees” and invited me to set up an apiary, I jumped at the opportunity. It was early May. Just days prior, I had been driving by his house — awestruck by the number of black locust trees hanging in a fragrant canopy over the road. It was a beautiful place to set up an apiary, with one problem — there were trees everywhere. The spot he chose for me, however, was a recently planted walnut grove nestled between two hay pastures. This apiary offered lightly dappled shade. So I gave it a try and found that I didn’t have more small hive beetle problems here than at any of my full-sun apiaries.

Fast forward ten years and a lot has changed. The walnut tree tops have grown into a denser shade. Also, there are probably ten more apiaries within two miles of this neck of the woods than there used to be. When apiaries form a tighter matrix of neighboring beehives, they share not only forage areas but also pests and diseases. So when I had a colony become weak after a late August queen supersedure, it became a target for late-season stressors like robbers and small hive beetles. One early November day, I went to deliver some thick sugar water and a mouse guard to this hive. To my horror, when I popped the lid I found as many adult hive beetles as bees. Beetles marched haphazardly all over the frames and piled on each other in corners of the boxes by the thousands — a scene from a beekeeping nightmare. I smashed hundreds of them, shaking out empty frames (that beetles had cleaned out, hungrily devouring contents from any open cells).

While I begrudgingly gave up 30 minutes to beetle smashing, I knew I was leaving behind far more than I killed. I reduced the hive by taking away a medium of 10 empty frames. I returned a few days later with a bottom board beetle trap, looking forward to snapping some terrifying SHB pictures I could use in this article. To my amazement, there were far fewer beetles than I had seen before — a manageable population for a normal hive. The bees looked calmer. I knew my smashing had done some good, and I knew that I could proceed with my management to “baby” this weaker colony through winter, rather than “take this loss in the fall.”

This isn’t the first time I’ve found myself surprised by a sudden explosion of SHB in a shady apiary. Because I have a family-type relationship with my apiary hosts, I don’t want to pick up and leave these shady sites. However, keeping these yards requires additional management to successfully keep bees under the trees. Let’s consider several pest and management options to help us stay ahead of these nasty little bugs, but let’s get to know them a little better first.

Not-fun facts about small hive beetles

Fact #1: Small hive beetles are repulsive. For me, the sight of them elicits a sense of disgust akin to sighting a house-dwelling cockroach. Their larvae are equally as odious, looking like maggots with racer legs protruding just below their heads. If your naked eye can barely stand the sight of SHB, try taking them under a microscope for a look at their hairy backs. Their fine fur helps them slip through honey bees’ tarsal claws, one of SHB’s many Houdini-type escape mechanisms. The dorsal hairs of SHB can host microorganisms like fungi and bacteria.

Since beetles love hanging out in sick, weak hives and then moving on to the next hive after they’ve decimated the first, they can cart around a lot of germs. They also transport a yeast (Kodamaea ohmeri) that ferments in bee-collected pollen, releasing odors that signal aggregation, attracting beetles from long distances. Interestingly one of the odor-producing elements is isopentyl acetate, the banana-scented chemical found in the honey bee alarm pheromone. It is notable that honey bee alarm pheromone is an attractant to SHB. When a colony robs another hive, or when a beekeeper causes significant upset during an inspection, this scent is broadcast over the airwaves, announcing “come as you are” party plans to opportunistic beetles far and wide.

Beetles are capable of smelling distressed hives and flying up to nine miles to congregate in and conquer a hive with any other beetles that picked up on the party invite. You may have experienced this dishearteningly quick turnaround. A colony appears healthy and strong one week, but two weeks later that same colony is on the verge of absconding, the hive filled with tens of thousands of adult beetles, larvae, and slime. In the two weeks between inspections, that hive was swarmed by beetles that could have come from anywhere. They entered “mass production mode,” something terrible for your neighborhood of apiaries.

Unfortunately, the droves of beetles don’t just move along to the next party after destroying a hive. “Mass production” means they produce enough offspring to establish a population in their chosen apiary. A study in 2004 found that 80 adult SHB could produce more than 63,000 offspring in two months’ time. In southern and coastal climates beekeepers will rotate apiary locations, because without freezing temperatures, beetles can maintain soil populations and become more abundant over time.

Fact #2: Small hive beetles spend a lot of time outside the hive. Not only can adult beetles shelter, eat, reproduce, and maintain full life cycles outside honey bee colonies, immature beetles can also survive for long periods of time under a variety of conditions in and outside the hive. In fact, immature hive beetles are in no hurry to grow up at all, though in high humidity SHB progress through immature stages quickly, with eggs hatching in just a day. Eggs usually hatch in three days or longer, staying viable for up to five days. Once hatched, larvae will feed in the hive anywhere from three to ten days. At this level of maturity, the larvae are at their most disgusting and will stay that way for a very long time, crawling wherever they please. This is called the wandering stage.

Larvae might wander for only a week, or they may aggregate in the hives, squirming around in a slimy mess with what looks like billions of other larvae. They can party like this for 20 days — it’s not unusual. Or they can wander around, looking for the perfect soil (loose, sandy, or silty) in which to burrow and pupate. Larvae can go two months wandering without eating. Once they begin their pupation process, they will take anywhere from two weeks to two months to pupate depending on soil type and soil moisture. We like to think that the SHB typical maturity time from egg to adult is between one and two months, but in reality, there are many variables, and like any successful invasive species, adaptability is the ticket to ride.

Fact #3: Hive beetles and their babies are hungry buggers. SHB like to eat lots of different things. As previously mentioned, SHB can live outside the hive, where they eat sugars and proteins from different sources. A study in 2008 found SHB could complete life cycles outside the hive when fed….