Years ago, I did some research into varroa mites for the Wannabees which is a group for young beekeepers in the Back Yard Beekeeper’s Association. In doing so I came across a statistic that mites can multiply 12 times in twelve weeks. So, if you start with 12 mites you would end up with 144 mites in twelve weeks, and that would be “gross”!

While at the University of Nebraska-Lincoln, Judy Wu-Smart published a paper on the Sublethal Effects of Pesticide Residues in Brood Comb on Worker Bees.   The two points that caught my eye involved the combined effect of chemicals on the length of time on brood. One is where the egg take’s 4 days instead of 3 to become larva, which the bees seem to remove at about day 8.  Thus, creating a spotty brood pattern. The other point involves the possibility of increasing the time of the capped pupa.

Varroa mites already have one reproductive daughter in worker brood, and rarely 2. Anything that adds time to the capped portion of the bee’s brood cycle will increase the chance of a second reproductive mite.  I found this interesting and decided to try and figure out where this 12 times factor comes from.

Once I had a method, I could change the percentages to see what could happen. In the following tables I make some assumptions, so it reflects only the reproduction of the mites.

  1. Overwintered mites die after producing 100 viable young mites.
  2. Varroa mites that hatch are baby mites, (B) which move to the next reproductive phase and become young mites(Y) and lay eggs. They leave a cell and move to the next cell and become mom mites(M) And lay another round of eggs. Then the mom mites die after the second reproductive cycle and are removed from the equation.
  3. Mite rearing starts February 1stwith 100 fertile mites.
  4. Bees have no resistance to mites, nor any attempt to reduce mite load by bees or beekeeper are taken.
  5. Drone brood is not counted.

Table One shows simple 1 to1 reproduction. Mite goes into a cell lays eggs, and because of the length of the bee’s development time only one new reproductive mite is produced. In three months, starting February 1st and ending at May 1st the math shows an increase of 13 times. I used 100% as opposed to 90 something % which skewed the numbers high, but I believe the math is correct. For the beekeeper, the numbers show how fast the mite population can grow and get out of hand.

Table Two represents the possibility of 2 reproductive mites as offspring in one bee brood cycle, due to an increase of the capped segment of the bee brood cycle. I stopped the math on June first when numbers spiked to over 200,000 mites.

Table Three is mites reproducing at a rate of 120%, I added 20% for drone brood and the occasional times when mites do have two reproductive offspring mites in worker brood. I stopped the math September first when mite counts would jump to over 400,000.

Thoughts to Ponder

Can chemicals in the comb increase the length of time of the capped phase of the bee’s brood cycle, thus increasing the rate of mite reproduction?

Can chilling the brood by the use of a screen bottom board also increase the time of capped bee brood cycle?

Are bees kept in large hives and encouraged to raise massive colonies, a breading playground for mites? Brood equals mites!

Are beekeepers sabotaging their own and other beekeepers with modern beekeeping practices ?????

Mites table 1

February  1            February 15                  March  1               March   15                 April 1

Over wintered            100y                                 100y                      200y                             300y

Mites Die                        0                                  100m                    100m                            200m

100b                         100b                                 200b                     300b                             500b

April 15                    May 1                             May 15                 June 1                        June 15

500y                          800y                                1300y                      2100y                           3400y

300m                         500m                               800m                     1300m                           2100m

800b                         1300b                               2100b                     3400b                           5500b

July 1                        July 15                           August 1                 August 15                  

5500y                       8900y                                14400y                     23300y

3400m                      5500m                               8900m                      14400m

8900b                        14400b                            23300b                     37700b

September 1          September 15              October 1               October 15

37700y                       61000y                              98700y                      159700y

23300m                    37700m                              61000m                    98700m

61000b                     98700b                               159700b                    258400b  


Baby Mites (b)            Become            Young Mites (y)              Become         Mom Mites (m)

These are the viable                             These are mites                                   These are the

New mites that mated                          that go into  a cell                               mites that laid eggs already

and emerge from cells                         to start reproducing                            and moved to a second cell

                                                                                                                       for another round of egg laying

Mites table 2

February  1               February 15                  March  1               March   15                 April 1

Over wintered        100y                                  200y                      600y                             1600y

Mites Die                       0                                   100m                    200m                            600m

100b                           200b                                   600b                     1600b                           4400b

April 15                     May 1                               May 15                  June 1                        

4400y                       12000y                               32800y                    89600y                        

1600m                      4400m                               12000m                   32800m                      

12000b                                   32800b                                                   89600b                                  244800b         

Mites table 3

February  1               February 15                  March  1               March   15                 April 1

Over wintered              100y                                 120y                       264y                             460y

Mites Die                        0                                   100m                      120m                            264m

100b                           120b                                  264b                       460b                             879b

April 15                     May 1                             May 15                  June 1                        June 15

879y                          1595y                              2958y                       5464y                         10107y

460m                          879m                               1595m                      2598m                        5464m

1595b                        2958b                              5464b                      10107b                        18685b

July 1                        July 15                          August 1               August 15              September 1

18685y                        34550y                          63883y                   118119y                     218403y

10107m                      18685m                         34550m                    63883m                118119m

34550b                       63883b                           118119b                   218403b               403826b