It’s a moment beekeepers dread. You head out to your hive to pay your bees a visit and see how they’re doing. As you open it up and go to pull out a frame, you’re faced with a frustrating and confusing sight. Your bees have built comb across frames, making it impossible to remove individual frames without damaging the comb.
It’s cross comb, and it happens in hives that belong to even the most seasoned beekeepers. There are a few reasons that cross comb can happen, but truthfully, it’s a common beekeeping hazard. Cross comb only occurs among the frames in hives where we place our bees. It doesn’t happen in the ones wild bees build in nature. This is because bees build wild haves on their own. In our hives, they are making use of the structure they are provided.
Don’t be discouraged, though! Even the most happy, comfortable, and well-taken-care-of bees build cross comb. As beekeepers, it’s our job to prevent it from happening and to deal with it carefully when it shows up in our hives.
Today we’re going to take a look at why and how bees build comb, what causes cross comb, and what you can do about it.
Comb is home to the most critical aspects of hive life. First of all, comb cells are the cozy quarters for eggs laid by the queen. It keeps the unborn bees safe and protected until they hatch into larvae. Once the larvae pupate, they come out of their cells as bees, ready to work at whatever role they have in the hive. We’ve told you all about workers, drones, and queen bees before.
The rest of the hive’s comb is all made for one purpose: creating and storing food. Worker bees deposit nectar into comb cells before converting it to honey and capping it to save it for later. They also pack away pollen into cells to preserve and keep it. If you weren’t able to grocery shop or prepare meals during winter months, you’d build one heck of a stockpile, wouldn’t you? It’s understandable, then, that bees work hard to create a structure that makes and keeps the food that will sustain them through a cold, forage-less winter.
Building comb starts with worker bees eating their fill of honey. At the ripe age of 10 days old, they develop eight glands inside their abdomens that metabolize honey into wax. It takes two tablespoons of honey to make one ounce of wax – that’s a lot of honey for a little bee to eat!
Then, in a warm hive (91-97 degrees Fahrenheit), the bees secrete the wax, or beeswax, through their abdomen pores. The beeswax hardens into little flaky bits of wax, or scales. Workers then munch on those scales, often eating it off of each other’s bellies. Then they softening it with their saliva enzymes. Next, the bees can start bonding together portions of the wax to construct the hive.
The bees get their site ready by spreading propolis over its walls. Propolis, often called “bee glue” in beekeeping circles, is a plant resin substance bees make. It’s very useful within the hive. Sort of like the epoxy humans use to fix things around the house, propolis is very efficient at sealing cracks and holes. It also strengthens construction in the hive.
Comb’s recognizable hexagon cells actually start as round, tubular structures. Then, as the bees do their work and generate enough heat (113 degrees Fahrenheit, to be exact) to warm the wax into a stretchy, liquid consistency. It flows into a hexagon shape, which is the shape that uses the least amount of wax to hold the maximum amount of weight.
The resulting hexagon cells, built in horizontal rows, are big enough for bees to fit into. They use the cells to clean, store food, and feed brood. The cells can also withstand a significant amount of weight. Since bees produce anywhere from 300-500 pounds of honey, the comb must be strong enough to store it all in the winter.
When they’re out in the wild and building their hive independent of humans, bees will typically construct comb in a “U” shape hanging downward. More comb is formed toward the top to secure it to the surface it’s built upon, with less comb added toward the bottom. This helps the structure hang with stability. In top bar hives, like the ones we make at Beepods, bees build their comb very similarly to these top-down structures they create in the wild, hanging downward within each frame.
In a perfect world inside the hives we provide them with, bees would build their comb within each frame without ever crossing onto another. But when the bees construct cross comb, it connects two or more frames in a hive. As you can guess (or perhaps, you’ve experienced yourself), this can create a mess for beekeepers.
Cross comb makes performing routine inspections challenging. You don’t want to risk tearing the comb away from either frame that shares it when you remove frames from the hive. As I mentioned earlier, cross comb is a problem exclusive to bees kept in hives. When it happens, it’s often a result of the hive environment, location, and structure.
Space is another reason bees might build comb between two frames. Bees will build comb anywhere they have enough space. If the opportunity presents itself, they might think, “Hey, why not build here?” Then they’ll construct their comb sideways instead of downward.
How we define open space is key here, because there is a precise measurement that determines where bees will build comb. The 3/8th of an inch principle (or “bee space”) suggests that bees will build comb any space bigger than 3/8 of an inch. They’ll fill any space less than that with propolis. The 3/8 of an inch measurement is the magic size that lets bees build comb while still moving around the hive.
Another reason bees build cross comb is gravity. If your hive isn’t on a completely level surface, bees will sometimes naturally build comb in the direction a hive might lean. Bees are little architects and will build their comb structures to be as strong as possible. Gravity can motivate them to build in a curve, or outward from the frame. Leveling your hive is a crucial step to keep this from happening. We’ll be talking more about that next week on the blog!
The best way to manage cross comb is to avoid letting it happen in the first place. Since bees will build anywhere they have bee space, it’s essential to make sure your hives are sized correctly and placed on level ground. If you don’t have the luxury of nipping it in the bud, there are a few things you can do to manage it.
Many cases of cross comb result from the bees initially building in straight formation, before shifting toward another frame. For these scenarios, gently break the cross comb from the top, bottom, and both sides of the frame. You can use a tool meant for this work, such as the Beepods Hive Tool. The Hive Tool is used to gently pry and scrape comb inside a hive. Then, you can carefully push the original comb back toward its frame. Secure it there – we like to use zip ties to do this – and to encourage the bees to build correctly.
If your cross comb situation is more serious, and a simple salvage like what I described above won’t cut it. Fixing it won’t be quite as easy. Advanced cross comb can consume many frames in a hive, making it pretty tough to salvage comb. In these cases, it’s best to carefully make as few cuts as possible to the comb to separate the frames. Recover as much of the comb as possible, and collecting what breaks off. Then, secure the remaining comb in their correct frames (again, we like zip ties, but some beekeepers opt for rubber bands).
We have a helpful video on how to repair comb that you can find here.
Cross comb is a headache for beekeepers, but ultimately, it’s a result of the man-made hives we place them in. Bees are merely doing their best in the home we give them! The best way to deal with cross comb is to avoid it with careful hive planning. If it happens, though, you can manage it and correct their mistakes. Hopefully, your bees will get on board with building comb in the direction they should!