Honeybee Diseases

In addition to fighting off varroa mites, wax moths, and small hive beetles, the hive also has a variety of viruses and bacteria to contend with. Mites serve as a vector for many of the viruses and high mite counts increase the chance of hive infection. There are no medication treatment for viral infections. Below is a general outline of the most common diseases, signs and symptoms, and treatment options. This article is intended as a broad overview, not specific treatment instructions.

  • Nosema: a spore forming organism that attacks the midgut of an adult bee. The most common adult ailment, leading to reduced honey yield, queen supersedure, reduced worker life, and decreased ability for nurse bees to feed brood. Signs include bees that can’t fly and won’t take syrup, restless and twitchy behavior, swollen abdomens, absconding, and bees defecating in hive. Natural treatments include providing fresh water, requeening, destroying frames soiled by feces, placing the hive in a sunny location, providing supplemental feed, and top entrances for additional ventilation. Chemical treatments are to feed the antibiotic Fumagillin-B.
  • Dysentery: resembles nosema but is a condition, not a disease. It is uncontrollable diarrhea secondary to poor feed and long periods of confinement. Do not allow your bees to feed on fermented honey, raw sugar, organic sugar, brown sugar, or any syrup other than white granulated sugar syrup. These products contain chemicals and solids that the bees cannot digest.
  • American FoulBrood: spore forming bacteria. The bacteria grows in the bee’s digestive system and produces spores that can live on equipment for up to 80 years. The bacteria is spread through reusing old equipment, bee drift, swarms, or contaminated honey. Signs include spotty brood, larvae that die upright in the cells, sunken cappings over dead brood, putrid odor, dead larvae rotting into glue-like scales that are difficult to remove. The Ropy Test is when you insert a toothpick into the dead larvae and pull it out. If the larve is ropy and stretches out to an inch, that is indicative of American FoulBrood. Results should be confirmed by a bee lab or state inspector. Treatment is to kill the bees with a fast acting insecticide or by spraying them with soapy water. Dig a pit 1-2 feet deep and burn all hive parts, covering the ashes with dirt.
  • European FoulBrood: bacterial disease commonly found in stressed or weak colonies. Dead larvae form scales that are easily removed. It is transmitted in the same manner as American FoulBrood. Larvae die in a twisted position and the hive may smell sour. Natural treatments include requeening the hive, breaking the brood cycle,, relocating the hive to prevent the spread of the disease through drifting, and provide supplemental feed. The chemical treatment for European FoulBrood is and antibiotic called Tylan.
  • Chalkbrood: a fungus that weakens a hive but does not generally kill it. The larvae will be mummified, beginning as a white color but eventually turning black. Chalkbrood spores are viable for up to 15 years and are spread by robbing bees, on used equipment, by the wind, and is present in the soil and water. Natural treatment includes making sure the hive is a dry, sunny location, requeening, adding bees for strength, providing supplemental feed.
  • Deformed Wing Virus (DWV): most common virus, vectored by mites. Worker bees emerge with stunted twisted wings and are ejected from the hive. You will sometimes see them crawling on the ground in front of the hive.
  • Sacbrood Virus: a virus causing scattered brood pattern, leather larvae that decompose into fluid filled sacs
  • Black Queen Cell Virus: infected brood and brood cells turn black
  • Israel Acute Paralysis Virus: causes adult bee paralysis
  • Acute Bee Paralysis Virus: causes tremors in adult bees during periods of high mite infestation

Most of the problems within a hive can be prevented with young queens, a mite treatment strategy, strong hives in sunny locations, the proper feed, and being very cautious about reusing old equipment.