Roe Valley Beekeepers Association
click the image to open a link to this document, which provides comprehensive advice on the recognition and treatment options for this ubiqutous and important disease vector
Varroa mites are external, obligate parasites of worker and drone honey bees. Varroa mites are visible with the naked eye and look somewhat like a tick. They feed on the hemolymph of adult bees and the developing brood. The reproduction cycle of the mite takes place inside the cells. Female mites (foundresses) enter the brood cells of last stage worker or drone larvae just prior to the cells being capped. There she will deposit five to six eggs over a period of time while feeding on the brood. The first egg laid will be unfertilized and develop into a male. The subsequent eggs will be fertilized and develop into females. The eggs hatch and the young mites begin to feed on the developing pupa. It is normal for mating to occur between siblings. The adult female mites along with the original female mite(s) leave the cell when the bee emerges. The female mites will enter another cell or attach themselves to an adult bee to feed. Varroa mites are transported from colony to colony by drifting or robbing bees.
Visible symptoms of Varroa mite damage can be evident on newly-emerged bees which is due to the mite feeding on the immatures within the cell. The newly-emerged bees may be smaller than normal, have crumpled or disjointed wings, and shortened abdomens. The lifespan of the newly emerged bee is also reduced. Severe infestations of Varroa mites within the cell (5 or more) can cause death to the pupa. Other symptoms of mite infestation are rapid colony decline, reduced adult bee population, evacuation of the hive by crawling bees, queen supersedure, spotty brood, and abnormal brood with symptoms resembling European foulbrood and sacbrood disease. These effects may be as a esult of transmission of viral infections. Infested colonies will die within 1 to 2 years if the beekeeper does not take necessary actions against Varroa mites. Varroa mites prefer drone brood over worker or queen.