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All bees are holometabolous insects. That’s a long way of saying they undergo complete metamorphosis. And that’s a long way of saying they have four life stages: egg, larva, pupa, and adult. Got it? Excellent! The rest is easy.
Like lots of similar insects, many bees spin a cocoon as they transition from a larva into a pupa. You may have seen the cocoons of mason bees which are firm and brown. Or you may have seen the cocoon of a butterfly or moth. In all cases, the cocoon safely seals the pupa from the outside world. But trapped inside, it cannot eat or defecate.
Eating and fasting stages
If you analyze the four life stages, you will see that the egg is a non-eating (fasting) stage. The egg is followed by the larva, which is an aggressive eating stage. Next, the pupa is the second fasting stage. After that, the adult is another eater. Clearly, the stages alternate between eating and using what was previously eaten.
To say larvae are aggressive eaters is something of an understatement. The larvae of butterflies and moths can mow crop plants to the ground. Right now, for example, cabbageworms, the larvae of the cabbage white butterfly, are devouring cole crops across the continent. Incredibly, about 85 percent of the worst crop pests are larval stages of some innocuous-looking insect. On the bright side, however, the larvae of the introduced cinnabar moth are chewing their way across pastures of tansy ragwort.
Larvae eat themselves silly
Honey bee larvae have equally voracious appetites. Some sources estimate that a honey bee larva increases its weight 1500 times in 5.5 days. That kind of growth requires serious munchies.
The food digested by the larvae is stored for use during the pupal stage when the bee transforms into an adult. Spinning the cocoon is one of the first things that happens as the larval stage comes to a close.
Rolling into a cocoon
Inside the newly capped brood cell, the larva does a somersault similar to the forward rolls you did in elementary school. As the bee rolls forward, it produces four substances. The silk glands, which are in the mouth, secrete a clear substance in long strands. In addition, three more substances are excreted from the anus: one is clear, one is yellowish, and one is feces.
As the larva somersaults within the brood cell, the cocoon materials exude from the bee’s body. But unlike a moth, butterfly, or solitary bee, the cocoon sticks to the inside of the brood cell. While you might imagine a butterfly cocoon being like a mummy case, the cocoon of a honey bee is more like wallpaper: they hang it up and leave it there.
Honey bee cocoons stay behind
After the pupa develops into an adult, the bee emerges from her natal cell, leaving the cocoon behind. Glued to the brood cell, the cocoon will not release. The feces is wrapped tightly within the other cocoon substances, nature’s way of assuring feces does not contaminate the inside of the brood cell.
Since the cocoons stick forever inside the comb, we never see a cocoon that looks anything like those produced by solitary bees or other insects. What we can see, however, is the forever darkening color of brood combs after successive generations of bees have left their cocoons and feces behind. The people who measure such things say that the inside of brood cells actually gets smaller over time, due to the build-up of multiple cocoons and metabolic waste.
Rusty Burlew
Honey Bee Suite
If anyone was uncertain as to the stuff inside a comb just melt it down to try to recover the wax. Man what a bunch of nasty stuff you can strain out – and most of that is just this – bee cocoons.
Melting down just the cappings after a harvest is a lot different than recovering wax from old combs – and worse yet combs damaged beyond salvage by wax worms. Those buggers are just awful.
And this is why I don’t want brood in my honey supers. Ugh!
Can we all just agree that Life is disgusting? : )
Roberta,
I had one of those moments yesterday. I was typing away on my laptop while my cat was walking back and forth across the keyboard, which causes my spellcheck to freak. Then, I looked down to see a tapeworm inching across the back of my hand. Why must cats get tapeworms? And why must they crawl out to investigate? I dislike their white color, and I especially dislike the shape of their heads. I politely walked it outside, but why, I do not know.
Hah. It once took me inordinately long to identify the parasite crawling out of my cat’s butt because I did not realize that an individual segment of a tapeworm could crawl, and in fact, the segments come out to reproduce. Ugh. Ugh. Ugh.
You shouldn’t’a walked that outside; you should have thrown it in the fire. With prejudice.
Also, apologies for being off-topic now, but [whiny eight-year-old voice] you started it.
My cat started it.
Thank you for this informative piece. I’ve never heard that the darkness of old brood comb is mainly left cocoons. Or that the cell gets smaller each year. The more reason to replace with new foundation regularly.