Varroa Mite

Varroa mites are external honeybee parasites that attack both the adults and the brood, with a distinct preference for drone brood. They suck the blood from both the adults and the developing brood, weakening and shortening the life span of the ones on which they feed. Emerging brood may be deformed with missing legs or wings. Untreated infestations of varroa mites that are allowed to increase will kill honeybee colonies. Losses due to these parasitic mites are often confused with causes such as winter mortality and queenlessness if the colonies are not examined for mites.

The adult female mites are reddish-brown in color, flattened, oval, and measure about 1 to 1.5 mm across. They have eight legs. They are large enough to be seen with the unaided eye on the thorax, most commonly, and on the bee’s abdomen. Their flattened shape allows them to hide between the bee’s abdominal segments. This mite is often confused with the bee louse, but the bee louse has only six legs, is more circular in shape, and is slightly larger.

Life cycle:When female mites are ready to lay eggs, they move into brood cells containing young larvae just before the cells are capped. They go to the bottom of the brood cells and immerse themselves in the remaining brood food. After the cells are capped and the larvae have finished spinning cocoons, the mites start feeding on the larvae.They begin laying eggs approximately three days after the cell has been capped. A fertilized female mite lays a total of 4 to 6 eggs.

The adult female and its immature offspring feed and develop on the bee as it matures.The egg, two eight-legged nymphal stages , and the adult. The period from egg to adult takes about 6 to 7 days for the female and 5 to 6 days for the male.Mating occurs in the brood cells before the new adult females emerge. The adult males die after copulation since their mouth parts are modified for sperm transfer rather than feeding. The old female and the newly-fertilized female offspring remain in the brood cell until the young bee emerges.

The adult bee serves as an intermediate host and a means of transport for these female mites.Varroa mites have a definite preference for drone brood. More mite offspring can mature during the longer development time of the drones.However, worker brood also is attacked. Queen brood is attacked only in cases of heavy infestation. Female mites produced in the summer live 2 to 3 months, and those produced in the fall live 5 to 8 months. Withoutbees and brood, the mites can survive no more than 5 days.

live in a comb with sealed brood at 68oF for up to 30 days.We do not know precisely how varroa mites spread so rapidly. We do know that these mites can be spread by the movement of honey bee colonies ,the shipment of queens and package bees, and the movement of colonies for pollination rentals.Beekeepers probably spread an infestation from one colony to another through normal apiary manipulations.Infestations also are spread as a result of drifting from one apiary to another and swarming bees.

Damage:Individual developing bees, if infested with one to two adult mites (and offspring), usually emerge without visible damage and are normal in appearance. They may, however, suffer from malnutrition, blood loss, or disease. Individuals that are heavily-infested with more than a few adult mites (which produce as many as 20 nymphs) usually become visibly crippled or die in their cells without emerging. In addition to the loss of hemolymph, varroa mites are known to transmit a number of pathogens including several viruses.When adult bees are infested with two or more mites, they become restless and fly with difficulty.

Their life span is generally shorter than unparasitized bees and they perform tasks poorly.On a colony level, the symptoms of a varroa mite infestation depend upon the degree of infestation. Lowlevel varroa infestations are difficult to detect. Medium-to high-level infestations may result in the appearance of a spotty brood pattern, as well as the presence of malformed worker and drone adults with deformed wings (may be associated with deformed wing virus) and small abdomens. Such bees are often unable to fly and can be seen crawling. Bees will uncap and throw out infested brood, which can sometimes be found at the hive entrance. Parasitized pupae will appear to have small, pale or dark-reddish brown spots on their normally white bodies. Colonies become severely debilitated as mite populations reach extremely high levels at the end of the broodrearing season.

Control: A wide-mouth mason jar with a tight fitting lid. Alcohol or any commercially available engine starter fluid Brush or shake approximately 100 to 200 worker bees sampled from near the middle of the hive into the wide-mouth mason jar. Place the lid on the jar of captured bees and spray a short burst (about one second) of engine starter fluid (approximately two teaspoons of alcohol) into the closed container. After about one minute, gently roll the jar from side to side to coat all of the bees with the ether (alcohol). If varroa mites are present, they will fall off of the bees and adhere to the sides of the jar where they can be counted.

Powdered-Sugar Shake A wide-mouth mason jar with a two-piece lid. Remove the center portion of the lid and replace with #8-mesh screen. #8-mesh (3 mm x 3 mm mesh) hardware cloth or any other mesh that will retain the bees while letting mites pass through Tablespoon measure Powdered sugar Brush or shake approximately 100 to 200 worker bees sampled from near the middle of the hive into the widemouth mason jar. Replace the modified lid and add a heaping tablespoon of powdered sugar through the mesh screen. Roll the jar from side to side to distribute the sugar over all of the bees. Wait a few minutes and roll the jar again.

Pour the sugar and dislodged mites through the screen onto cheesecloth. Separate the mites from the sugar by sifting the sugar through the cloth, leaving the mites on the cloth surface.The bees can then be returned to the colony where their hive mates will groom them clean because the sugar stimulates the bees’ grooming behavior. The powdered sugar makes it difficult for the mites to adhere to their host, causing the mites to fall off the bees.

If you have any questions about how to get rid of mites check out the rest of our website or go to our blog at http://nypestpro.blogspot.com.

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