This comes from the April Issue of APIS, newsletter of the Florida Cooperative Extension Service and is in response to detection/treatment levels. As S. Bambara says, it's best to determine a ball park figure and not treat when only very few mites are detected. VARROA DETECTION The rest of the United States is starting to realize what many beekeepers in Florida have learned in the last two years. Varroa mites are here to stay and monitoring the mite population is the best way to keep parasite populations low. Dr. Eric Mussen in his January/February 1992 issue of From the UC Apiaries published a piece called "Varroa Getting Nasty." It seems many beekeepers in California got a surprise when their colonies collapsed last fall. The symptoms at first seemed to be classical for tracheal mites: 1. rapid loss of adults; 2. tiny clusters of bees with a queen; and 3. abundance of stored honey and pollen. Not characteristic was varying amounts of capped brood. The latter revealed that something else was going on; the adults were not being replaced. Developing pupae were killed in their capped cells by mites and never emerged. To prevent colony collapse, Dr. Mussen suggests checking bees for Varroa two to four times per year. Finding a mite or two doesn't mean the colony is in immediate jeopardy, but it will require treatment sooner or later. And if another check, not too much later, turns up a lot of mites, then you are the unlucky recipient of someone else's failure to detect a problem. Choose your method of colony examination (ether roll, tobacco smoke, Apistan), he concludes, early detection is critical to colony protection. "Looking for trouble," is the way Dr. Roger Morse categorizes the perpetual hunt for Varroa in the April, 1992 issue of Gleanings in Bee Culture. He concludes, "...in all probability every beekeeper in the continental U.S. and Canada will have infested hives within two to four years." He recommends, therefore, that beekeepers in the U.S., Canada and Mexico check colonies for Varroa at least twice a year. Although it has been reported that colonies sometimes take years to die after being infested with Varroa, there are exceptions. Dr. Morse speaks of a New York beekeeper whose hives produced over 100 pounds of honey in July and August, yet were dead by late fall. And Dr. Mussen describes a California beekeeper, who after a good producing season, saw 75% of his colonies severely damaged or dead by Christmas. That beekeeper is no longer in business and had to sell out at submarket prices. These cases may be because of drift by bees from nearby heavily infested apiaries that were not treated. Also the fact that mites are hidden and protected in capped brood cells may mean a serious undercount in those found on adults or in bottomboard debris. Fortunately, detecting Varroa is a fairly simple process. A number of methods are described by Dr. Morse, including: examining brood or adults; sorting through bottomboard debris; and using the ether roll. These are well documented in Varroa Mite Detection, VT 249, produced here at the University of Florida. I can have a copy made and sent upon receipt of a blank VHS videotape. The technology to determine when a Varroa infestation reaches a treatable level by any detection method currently in use has not been well worked out. Detection results may vary and are dependent on bee/mite population dynamics. For example, in the fall, Dr. Morse says, with little or no brood, you are more likely to find mites on adults, whereas in the spring they will be easier to find in brood. Practical experience by the Florida Division of Plant Industry indicates that when 20 mites in an ether roll of approximately 300 adult bees are found, a colony should be treated with Apistan. However, Dr. Harvey Cromroy of the Entomology- Nematology faculty, University of Florida, believes more than five mites is a treatable level. Dr. Morse concludes finding 30 to 40 mites per hundred bees (ether roll) is serious and the colony may be beyond saving. The ability to correlate ether roll with other detection methods is not presently available. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Tom Sanford Extension Apiculturist University of Florida Mailing Address: Bldg 970, Hull Rd., Gainesville, FL 32611-0620 Voice phone 904/392-1801, Ext. 143 FAX 904/392-0190 INTERNET: [log in to unmask] BITNET: MTS@IFASGNV +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++