Ever pull out some frames to discover the bees have built comb perpendicular to the frames and every which way? I have. It’s called cross-comb and it’s a mess. Here’s my first look at it from late July:Cross-comb is usually the result of a hive that isn’t level, specifically when it’s tilted, even a little bit, to the left or the right. Bees follow the pull of gravity to build comb straight down. That’s pretty much what they’re up to when you see them festooning: The bees don’t care about the frames or foundation inside the frames. If the frames or foundation happen to be parallel to the Earth’s gravitational pull, then the bees will build straight comb that fits conveniently on the frame just that way we humans like it. If not, the frames — and the foundation in the frames — only get in the bees’ way and you end up with cross-comb. That’s why the ideal positioning of a Langstroth hive is level from left to right — to prevent cross-comb — and slightly tilted up on the back so that any moisture that happens to collect inside the hive will pour out the front entrance and not pool inside the hive.
ADDENDUM (April 05/14): I used to carry a carpenter’s bubble level with me whenever I set up a new hive (the hives can shift over winter as well, as I learned today), but these days I use a Bubble level app on my cell phone. (I happen to have an Android phone, but I’m sure similar apps are available for other types of smart phones or devices.) There are many free apps to choose from and, for me, I’d rather have an easy-to-use app already on my phone if it means I don’t have to carry around another piece of equipment when I’m tending to the bees.