swarms from beekeeping operations. Practically speaking, the wild honey bees have become extinct in the United States due to infestation of the Varroa mite.
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 or viruses that are associated with varroa. 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 foundresses) 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.
Infested colonies will die within 1 to 2 years if the beekeeper does not take necessary actions against Varroa mites. If upon initial examination of your colony you do not see visible mites, use a capping scratcher on drone brood to see if Varroa are inside cells. Varroa mites prefer drone brood over worker or queen. If mites are detected you may need to treat in order to save your colony. At this time there are a few chemical treatments available for Varroa mite control in the US: Check Mite strips (active ingredient coumaphos), Apistan (active ingredient fluvalinate), ApiGuard or ApiLifeVar (active ingredient thymol), and MiteAway II (active ingredient formic acid). Always follow manufacturer's instructions when using chemicals. Also, never treat during a nectar flow because the chemicals can contaminate the honey, and never leave strips or applicators in hives after the recommended time because this encourages resistance. In recent years, mite resistance to Apistan and CheckMite+ strips has become a problem throughout the world. Therefore, rotating chemicals, delaying treatment and using cultural controls are recommended to manage mites in a more sustainable manner.
Delaying treatment can be accomplished if you monitor the level of Varroa infestation in your colonies. Treatment is justified only when the economic threshold is achieved. Economic thresholds are defined as the pest level that justifies treatment in order to prevent the pest from reaching damaging levels. For the southeast Piedmont region, the economic threshold has been determined to be:
mite populations: 3172-4261 ether roll levels: 15-38 overnight sticky sheets: 59-187
Ether rolls are easy to do and require little work. Take a quart jar and fill with about 300 bees (1.5 inches of bees). Then spray some ether engine starter fluid into the quart jar and replace the lid. Shake the jar for 30 seconds. The mites will dislodge from the bees and stick to the sides of the jar. Count the number of mites and compare them to the numbers above. A similar method (and easier alternative) to ether rolls are powdered sugar shakes. It requires a jar with 8-mesh hardware cloth lid. Fill the jar with about 300 bees and 2 tablespoons of powdered sugar. Allow the bees to move around the sugar and shake the jar (not upside down) for about one minute. Turn the jar upside down and shake the sugar onto a clean, white surface. Count the number of mites and use the recommendations for