Varroa douple itself in month - need to kill them?

[Finski]

Varroa douple itself about in month. How importan it is to stop reproduction?

 In winter after brooding season it is idea to slow down the mite population that it has no time to become a harm in late summer for winter bee rearing.

In late summer mites concentrate into last brood which ought to be winter bees.  

Lets calculate how the population grows
20      ….      40      ….      80      ….      160      ….      320      ….      640      ….      1280 / September
Marsh...

5      ….      10      ….      20      ….      40      ….      80      ….      160      ….      320

100      ….      200      ….      400      ….      800            1600            3200      .      6400 /Sept


1000 mites is a limit of bad contamination


.

[Finski]

.
Do I need to kill them

After treating I may have 5 mites in spring and  300 in next Autumn. Do I need them. Nothing bad has happened.


Let's suppose that during winter 320 mites has dropped to 100. Next September I will have 6 000 mites.

Lets treat them with efficacy  98%. What means 2%?

3200      …>      64.. ... ... next August 2000  .. Sept 4000 ...Oct  8000

640      …>      13..   ... ...  next Sept  800 .. Oct  1600

160      …>      3  .. ... ..  next Oct 400



WHAT I TELL: TREAT MITES EVERY YEAR!

If you do not see mites with mere eyes in young bees, you may have 300-500 mites in the hive.

If you see them several with mere eyes, the count may bee about 1000. It needs late summer treatment before winter bees rearing.

.