Beekeepers sometimes report unusual behaviors in their bees, everything from fore-and-aft convulsions to unmitigated quaking anger. I’ve collected three of these observations below, each from a new beekeeper:
“Today a bee on the landing board was trying to vomit. Her whole body was wracked with convulsions that moved in waves. When I opened the hive, I found others pulsating in the same way. I’m worried. What should I do about these sick bees?”
“I think my bees have been sprayed with insect killer. Some of them are showing muscles spasms in their abdomens that don’t stop, and I’ve read insect poison will do that. Except for the contractions, they are acting kinda normal. What do you think?”
“Bees on the front of my hive are so angry, I ran away. They are mad, acting like they’re in labor, or having seizures of fury. It’s hard to explain but it’s like a wave of tension that flows from one end to another and it happens over and over. Should I just wait or what? What made them so furious?”
A condition with a name
Luckily for us, this well-known condition has a name. It’s called breathing.
Animals, including insects, need oxygen for survival, and complex multi-cellular animals need ways to deliver oxygen to all the cells and organs inside the body. Many different breathing systems have evolved, and each system works for the particular environment where the animal lives.
Bees, like many other insects, have a system of tracheal tubes that move oxygen throughout the body. These tubes are long with many branches that get smaller in diameter as they go further in. They start at the integument (skin) of the insect and grow inward in a complex matrix.
The tracheae deliver
The tracheae deliver oxygen to wherever it needs to go because, unlike human blood, insect hemolymph does not carry oxygen. At various places along the tracheae, thin-walled balloons or pillows fill up with oxygen, expanding and contracting as needed. In many ways, these sacs act like lungs, bringing in oxygen and pushing it where it needs to go. Honey bees have air sacs in their head, thorax, abdomen, and legs.
Muscle movements in the abdomen control the movement in and out of the air sacs. These telescoping movements have been described by scientists as “accordion-like.” The muscle contractions seem to flow along the length of the abdomen causing the abdominal plates to slide over or under one another.
The whole body appears to move because the muscles attach to the inside of the segments, not the air sacs. The bee can contract her muscles dorsoventrally (from top to bottom) or along the length of the abdomen. As the abdomen contracts, air is squeezed from the sacs and as the muscles relax, air is sucked into them, much like a bicycle pump.
The spiracle miracle
Each tracheal tube attaches to the inside of the integument at a point called a spiracle. Basically, a spiracle is just a hole through the integument that has a one-way valve so air can come in easily but cannot escape. This means when the bee contracts her abdomen, the air moves inward to the organs and not back out through the spiracle. Pretty neat. Bees have ten pairs of spiracles, three pairs on the thorax and seven pairs on the abdomen.
The spiracles connect to the widest part of the tracheal system. As you travel along the tubes, they get smaller in diameter with thinner walls. At the very ends of the tracheal branches are the smallest tubes called tracheoles. From these terminal points, the oxygen moves by diffusion into the tissues that surround them.
Spiracles are different sizes and unfortunately, the first pair, the two closest to the head of the bee, are large enough to allow other small items to enter. The worst of these other items is the tracheal mite.
Control of oxygenation
Bees can increase the amount of oxygen going to their organs by increasing the number and size of muscle contractions. This “heavy breathing” is probably the thing that beekeepers notice and become concerned about. Although you can often see bees breathe if you look closely, the movements are very slight, but at other times they are quite pronounced. The amount of movement can increase due to oxygen depletion or decrease due to carbon dioxide elevation.
But don’t read too much into these variations. Heavy breathing does not necessarily mean anger or disease or poison or fear. It just means that, for some reason, the body needs more oxygen. Breathe easy and let your bee be the judge.
Honey Bee Suite