Worms in Bone Marrow? Probably Maggots

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A reader wrote to us about a fascinating discovery he recently made: when he split open a beef marrow bone – the type you might get from a butcher, which is where our reader got his bone – for his dogs to get at the marrow, he discovered that the bone was filled with hundreds, and perhaps even thousands, of tiny worms, or what appeared to be worms. The worms were inside the bone, burrowed into the bone marrow. Strangely, it appeared that the bone was completely sealed; in other words, it looked as though there was no way for anything to get into the bone. So, how on earth did an abundance of small worm-like creatures make their way into a bone, and what are these creatures anyway?

The reader specifically mentioned that he didn’t think the “worms” were maggots – that is, the larvae of flies – but, frankly, we can’t imagine what else they would be. To be sure, we haven’t specifically heard of maggots living in bones in the way described by our reader, but it still seems overwhelmingly likely that he did in fact come across maggots.

First, the reader described the creatures in the bone as very small, perhaps around 10 mm in length (for perspective, that’s a mere tenth of a centimeter) and about .5 mm in diameter. Guess what? That’s about exactly the size of maggots, and in fact they can be even smaller than that. The reader also said the creatures in the bone were a white or clearish color, which is also the typical color of maggots. (They can appear “clear” because you can sometimes see traces of the interior of maggots.) Finally, the environment in which the maggots were found – namely, bone marrow; indeed, moist bone marrow, according to the reader – is precisely the type of place you would expect to find maggots. A primary place where adult flies like to lay their eggs is damp food matter – think of those disgusting pictures of animal corpses being decomposed by thousands of maggots (ahh, the circle of life). If you’re a fly, bone marrow is a prime place to start a family.

But how did these maggots get into the bone to begin with if it was perfectly sealed? The answer is that the bone was most likely not perfectly sealed, however we’re to understand this phrase, and that flies exploited some opening to lay their eggs. Fly eggs are extremely small – they are about one to three mm long – and it seems likely that at least a portion of the hundreds of eggs flies lay could get into the bone marrow. Once the cycle has started, fly populations grow exponentially, so if the first eggs grew into flies, and these flies laid more eggs in the bone marrow, it’s not surprising that our reader found a huge amount of maggots when he cracked open the bone.

As a concluding note, the reader asked about any danger associated with the creatures he discovered. The short answer is that maggots can cause problems for animals and humans; for example, maggots can cause myiasis, which involves fly larvae feeding on a host’s tissue and liquids, as well as its ingested food. This is a major problem in the livestock industry, which probably explains why our reader found the maggots in a beef bone acquired from the butcher.

Could our reader have discovered something other than maggots, as he originally believed? We suppose so, but from all the information we were given, it seems very likely that he was dealing with plain old maggots.


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