Varroa Mites - The Scourge

varroa mites in american bee colonies were first reported in 1986, and is now one of the major killers of bees. adult female mites are found on bees - they attach themselves to the soft tissue between abdominal segments or behind the head. the mites breed in the drone brood, but will also invade worker brood. the result of mite breeding in the pupae is a disfigured, stunted adult bees, with deformed legs or wings or both.  lawrence and i did a drop test for mites in july.  we have a white, plasticized piece of cardboard which is lined for a grid, which fits below the bottom screen of the hive. it is greased  with vaseline.  you leave it under the hive for several days and then remove it to make a visual count of mites that have dropped down.  the picture below shows two mites.

the beekeeper can spot bees with mites attached with the naked eye.  you can even remove them with a toothpick, but that is a bit of a challenge for hundreds of bees.  the mites attach themselves on the upper back of the bee because that is the spot that the bee can't reach to dislodge them.  bees will also groom each other, so some beekeepers dust the bees with powdered sugar throughout the summer to encourage grooming. 

mites in hives can cause damage to the developing bee, either by feeding on them or by an associated virus, which deforms their wings (deformed wing syndrome).  these poor little things can't really do any work in the hive and you will see them being flown away by the undertaker bees.  in the hive, you can see them hiding in cells (head down).  

needless to say, controlling and treatment of mite infestation is an important task for the beekeeper.  there are various products available to knock down the mite population in the hive. one is called apivar, which is a slow-release miticide that is effective, but requires that you remove honey supers to avoid contamination.  another product are mite-away strips which use formic acid as a fumigant and miticide.  lawrence and i used the mite-away strips to treat all of our hives this weekend, but made a mistake in application, which resulted in a fair number of dead bees in our home hives.  we really hope that both jamaica and astoria are not affected and that they will suffer through the nasty treatment and bounce back in about 5 days. right now (third day of treatment) the bees are very, very unhappy with us. lawrence was stung on the ear, just walking around the hive yesterday. eeks!