MITE TREATMENT OBSERVATIONS UPDATE

In an earlier post (Mite Treatment Observations dated 21 August 2020) I reported on how FormicPro greatly knocked down the mite population in two hives.  One of the two hives, however, has seen a rebound in mite population as measured by its daily mite drop to witness board.  Recently there were several days where the mite drop hit 20 mites per day!  Without doing either the daily mite drop count or a follow mite test I would have never suspected the initial treatment with FormicPro had not cleared the hive of mites. 

A portion of this increase could be explained by the natural slowdown in brood rearing that occurs in late August.  But to be safe I applied another full dose of FormicPro to this hive.   Again, the mites rained down onto the witness board.  146 mites in the first 24 hours,  69 mites in the second 24 hours and a total of 366 mites over a period of a week.   

What is the point of this article?  1) Mite treatments are not always successful especially if the mite load is too great.  2) Mite checks don’t always reveal the true mite levels.  3) A beekeeper needs a backup plan. 

My backup plan is incorporation of a queen with mite resistant genetics.  So this weekend it will be off with the old queen's head and installation of a new queen with mite resistant genes. This is the standard recommended practice for someone trying to improve the mite resistance of their apiary; simply eliminate the hives (ie queens) associated with high mite levels.

As a side note the two hives with the Purdue Mite Biter and feral breeder queens continue to show low daily mite drops; on average of 1 to 2 mites per day.   I sure hope these good results continue until winter arrives and the hive temporarily stops brood rearing for the winter.   Then the mites can no longer reproduce since there will be no bee brood.   

Microscopic examination of the mites from these two hives shows a large percentage of the mites are missing legs, portions of legs and some mites even show damage to the carapace (outer shell).  This damage is the result of the chewing behavior exhibited by the offspring of these breeder queens.  I will be continuing counting and examining mites until November and summarize my observations at that time.  Here are two pictures; one of an undamaged mite and one that shows a mite which has had several legs chewed off.  Is this the answer to the varroa mite scourge?   I hope so!

View of the bottom of a varroa mite showing its 8 legs. 

  View of a varroa mites where several legs are either removed or shortened.

In my personal examinations I am frequently seeing mites with missing or damaged legs.