Tracheal mite on honey bee hair. T. C. Webster

Mites and eggs in honey bee tracheal system. USDA photo.

Tracheal mites were first detected in the United States in 1984 and have since caused the loss of tens of thousands of colonies and millions of dollars. Tracheal mites infest the tracheal system of the adult honey bee. Levels are highest during the winter and spring. Mites prefer adult bees less than four days old. Once they are on the bee, mites are attracted to carbon dioxide emissions and enter the spiracles located on the thorax which lead to the tracheal system. They puncture the wall of the trachea and suck the hemolymph of the bee. Tracheal mites live, breed and lay eggs in the tracheal system. The adults and eggs plug the tubes of the trachea which impairs oxygen exchange. They also spread secondary diseases and pathogens since they puncture the trachea in order to feed. Individual bees die due to the disruption to respiration, damage to the tracheae, microorganisms entering the hemolymph, and from the loss of hemolymph. Honey production may be reduced when over 30 percent of the population is infested with tracheal mites. Also, the likelihood of winter survival decreases with increasing infestation of the mite. Mites are transmitted from bee to bee within a colony and to other colonies by robbing or drifting bees.

Infested bees will be seen leaving the colony and crawling on the grass just outside the hive. They will crawl up the blades of grass or the hive, fall back down and try again. The wings may be disjointed and the bees unable to fly. The abdomens may be swollen. In late stages of infestation, bees will abscond from the hive. If you are unsure if you have tracheal mites, send a sample of bees in alcohol to your local county extension agent for verification.

One method for controlling tracheal mites is the use of menthol, available from most bee supply companies. The temperature must be above 60^° F in order for the menthol to work. The bees breath in the vapor which, it is believed, desiccates the mites. Menthol must be removed during a nectar flow in order to not contaminate honey.

Another less caustic treatment for tracheal mites is an oil extender patty. It consists of two parts sugar to one part vegetable shortening. Make a small patty about four inches in diameter and sandwich it between wax paper. Cut the wax paper around the edges so the bees have access to the patty. Center the oil patty on top of the frames within the hive body. The bees will be attracted to the sugar and obtain oil on their bodies. The oil acts as a chemical cloak and the tracheal mites are unable to identify suitable bee hosts. The oil patties are acceptable for prolonged treatment since the oil will not contaminate honey supplies.

Honey Bee Disorders / UGA Honey Bee Program / UGA Entomology Department