American and European foulbrood

It's late June. Anne pulls a brood frame and something is wrong. The brood is patchy. Some cappings are dark, sunken and greasy looking, and a few have small holes in them. And there is a smell, sour and rotten, that she has never noticed before. She puts the frame back, puts the lid on, and calls her mentor.

Her mentor asks one question first. Did you do the ropy test?

American foulbrood is the most serious brood disease a beekeeper can face. It's caused by a bacterium that forms spores, and it kills larvae after their cells are capped. There is no cure. The spores can survive in old equipment for up to seventy years, and a single dried remains of a larva can hold billions of them.

The signs are the ones Anne saw. Spotty brood. Cappings that are sunken, greasy or punctured. Larvae that turn from coffee brown to black. A dry scale stuck tightly to the lower wall of the cell. And that foul smell.

Then the ropy test. Push a twig or matchstick into a suspect cell, stir, and slowly pull it out. If the rotten larva stretches out in a brown thread about two and a half centimetres or more, suspect American foulbrood.

If you suspect it, you must report it right away to the Ontario Apiary Program. That is the law, and hiding it is an offence. An inspector will confirm the diagnosis. Hives confirmed with American foulbrood are burned, because the spores can't be cleaned away, and one infected hive can spread the disease for kilometres through robbing, drifting and shared equipment.

European foulbrood is different. It usually kills younger larvae, before their cells are capped. They often lie twisted in the cell, and turn yellowish, watery, and rarely ropy. The dried remains are rubbery and easy to remove. It is reportable too, and in twenty twenty five Ontario inspectors found it more often than the year before, and described it as harder to treat and manage.

What about antibiotics? In Canada, the antibiotics registered for foulbrood can only be used with a veterinarian's prescription. They are used to prevent disease, not to cure American foulbrood. And they must stop at least four weeks before the honey supers go on, so there are no residues in the honey.

The good news is that these diseases are uncommon. In twenty twenty five, Ontario inspectors found American foulbrood in about half of one percent of the colonies they checked. But when it appears, how fast you act decides how far it spreads.

Now let's change one fact. Suppose the sick larvae are young, twisted and watery, and they don't rope out on the twig. That points to European foulbrood rather than American. The response starts the same way: stop, don't move anything between hives, and call the Apiary Program.

The mistake beginners make is trying to handle it quietly, by swapping frames into other hives, selling the equipment, or waiting to see. That is how one sick colony becomes a sick neighbourhood.

Here is the rule, in one breath. Spotty brood with sunken, greasy or punctured cappings, dark larvae and a ropy thread means suspect American foulbrood; report it immediately, move nothing, and let an inspector confirm, because infected hives are burned and antibiotics need a veterinarian's prescription.

Next, the quieter diseases: nosema, chalkbrood, sacbrood, viruses and tracheal mites.