Honey Bees Disease and Pests

Honey bee brood and adults are attacked by bacteria, viruses, protozoa’s, fungi and exotic parasitic mites. Additionally, bee equipment is attacked by other insects. Disease and pest control requires constant vigilance by the beekeeper.

American Foulbrood – (AFB) is a bacterial disease of larvae and pupae. The bacteria form highly persistent spores that can be spread by adult bees and contaminated equipment. Infected larvae change color from a healthy pearly white to dark brown and die after they are capped. Cappings of dead brood sink inward and often are perforated. Check for AFB by thrusting a small stick or toothpick into the dead brood, mixing it then withdrawing the mass. Brood killed by AFB will be stringy and rope out about inch. Colonies with AFB must be burned by a state bee inspector.  To prevent AFB, feed colonies the antibiotic TerramycinÆ according to label instructions in early spring and fall. Allow at least four weeks from the last TerramycinÆ treatment until the first nectar flow.

European Foulbrood – (EFB) is a bacterial disease of larvae. Unlike with AFB, larvae infected with EFB die before they are capped. Infected larvae are twisted in the bottoms of their cells, change to a creamy color and have a smooth “melted” appearance. Because EFB bacteria do not form persistent spores, this disease is not as dangerous as AFB. Colonies with EFB will sometimes recover on their own after a good nectar flow begins. To prevent EFB, treat colonies with TerramycinÆ as described above.

Chalkbrood – Is a fungal disease of larvae. Infected larvae turn a chalky white color, become hard then turn black. Chalkbrood is most frequent during damp conditions in early spring. Colonies usually recover on their own.

Nosema – Is a widespread protozoan disease of adult bees. In spring, infected colonies build up very slowly or not at all. Bees appear weak and may crawl around the front of the hive. Discourage nosema by selecting hive sites with good air flow. Damp, cold conditions seem to encourage this disease. Treat nosema by feeding the drug FumidilÆ B in sugar syrup in spring and fall. Do not feed the medication immediately before or during a nectar flow.

Wax Moths – Are a notorious pest of beekeeping equipment. Adult moths lay eggs near wax combs, then their larvae hatch and begin burrowing through the combs to eat debris in the cells. Moth larvae ruin combs and plaster them with webbing and feces. Honey bees are usually very good at protecting their colonies from moth larvae. If moth damage is found in a colony, there was some other problem (usually queen loss) that weakened the colony first. Moth damage is most common in stored supers of comb. Protect stored supers by stacking them no higher than five hive bodies. Tape shut all cracks, put paradichlorobenzene crystals at the top of the stack and cover the stack with a lid. Replenish the crystals as they evaporate.

Tracheal Mites – These microscopic mites enter the tracheae (breathing tubes) of young bees. Inside the tracheae, mites block air exchange and pierce the walls of the tubes to suck blood. Symptoms resemble those of nosema. Bees become weak, crawl at the hive entrance and sometimes uncouple their wings so that all four wings are visible. Colony death rates are highest during winter and early spring. 

Varroa Mites – These mites are about the size of a pin head and are copper in color. Female mites cling to adult bees and suck their blood. Females then enter a bee brood cell and produce several offspring which, in turn, suck the blood of the developing bee. Infested colonies almost always die within three to four years unless they are treated.