Understanding Major Bee Diseases
Nothing is more devastating than losing a colony to disease. But honey bees, like any other living creatures, are susceptible to illness. You should be on the lookout for six honey bee diseases. Some are rare, and it’s doubtful that you’ll ever encounter them. Some are more commonplace and knowing what to do if they come knocking is important.
Each time you inspect your bees, you’re looking for two things: evidence of the queen (look for eggs) and evidence of health problems.
American foulbrood (AFB)
American foulbrood (AFB) is a nasty bacterial disease that attacks larvae and pupae. Some symptoms are
Infected larvae change color from a healthy pearly white to tan or dark brown and die after they’re capped.
Cappings of dead brood sink inward (becoming concave) and often appear perforated with tiny holes.
The capped brood pattern no longer is compact, but becomes spotty and random. This is sometimes referred to as a shotgun pattern.
The surface of the cappings may appear wet or greasy.
If you suspect that your bees actually have AFB, immediately ask your state bee inspector to check your diagnosis.
European foulbrood (EFB)
European foulbrood (EFB) is a bacterial disease of larvae. Unlike AFB, larvae infected with EFB die before they’re capped. Symptoms of EFB include the following:
Very spotty brood pattern (many empty cells scattered among the capped brood). This is sometimes referred to as a shotgun pattern.
Infected larvae are twisted in the bottoms of their cells like an inverted corkscrew. The larvae are either a light tan or brown color, and have a smooth "melted" appearance. Remember that normal, healthy larvae are a glistening, bright white color.
With EFB, nearly all of the larvae die in their cells before they are capped. This makes it easy for you to see the discolored larvae.
Capped cells may be sunken in and perforated, but the toothpick test won’t result in the telltale ropy trail as described for AFB.
A sour odor may be present (but not as foul as AFB).
It’s a good hygienic practice to replace all of the frames and comb in your hives every few years. There are a couple of compelling reasons for doing this: Replacing old frames minimizes the spread of disease.
Nosema, a common protozoan disease that affects the intestinal tracks of adult bees, is kind of like dysentery in humans. Some symptoms of Nosema are
In the spring, infected colonies build up slowly or perhaps not at all.
Bees appear weak and may shiver and crawl aimlessly around the front of the hive.
The hive has a characteristic spotting, which refers to streaks of mustard-brown feces that appear in and on the hive.
Chalkbrood is a common fungal disease that affects bee larvae. Chalkbrood pops up most frequently during damp conditions in early spring. It is rather common and usually not that serious. Infected larvae turn a chalky white color, become hard, and may occasionally turn black.
No medical treatment is necessary for chalkbrood. Your colony should recover okay on its own. But you can help them out by removing mummified carcasses from the hive’s entrance and from the ground around the hive.
Sacbrood is a viral disease of brood similar to a common cold. It isn’t considered a serious threat to the colony. Infected larvae turn yellow and eventually dark brown. They’re easily removed from their cells, because they appear to be in a water-filled sack. Now you know where the name comes from.
No recommended medical treatment exists for sacbrood. But you can shorten the duration of this condition by removing the sacs with a pair of tweezers. Other than that intervention, let the bees slug it out for themselves.
Stonebrood is a fungal disease that affects larvae and pupae. It is rare and doesn’t often show up. Stonebrood causes the mummification of brood. Mummies are hard and solid (not sponge-like and chalky as with chalkbrood). Some brood may become covered with a powdery green fungus.
No medical treatment is recommended for stonebrood. In most instances worker bees remove dead brood, and the colony recovers on its own. You can help things along by cleaning up mummies at the entrance and around the hive, and removing heavily infested frames.