Thursday, June 3, 2010

Checking bee pupae for mites

Ok some might find this a little gross or even heartless, but it's for the overall good of the bees.

My honeybees came from a 'natural minded' beekeeper who doesn't treat with pesticides for mite control or antibiotics for disease control. They seem pretty healthy and I've had them about six weeks. But one of the biggest problems honeybees face these days is varroa mites. Just about all hives in the U.S. have them now, or else they get them from nearby hives, so it's good to periodically get an idea of just how many mites there are amongst your hive population. Monitoring mite levels can give you a warning when something is going wrong and give you time to correct it in various ways.

To check for my hives' mite load, I first put a frame of specifically sized drone (male bee) foundation in each of my two hives. Varroa mites particularly target the larger drone cells in which to breed, attaching themselves to the drone larvae and pupae, sucking on them while the pupae develops in the capped cell, and emerging already attached to the adult drone bee. The affected drone bee is weakened and sometimes deformed by the mites, and the mite reproductive cycle continues.

Yesterday I removed the two 'mite bait' frames of capped drone brood from my hives, put them in the freezer overnight to quickly kill the larvae and whatever mites might be there, then I thawed the frames today to examine them.
I was delighted to find almost no mites at all on the drone larvae and pupae. I pulled about 30 dead drone pupae from their cells, and among the 30 I found only one lone varroa mite.

In this picture you can see the capped drone brood still on the frame in the background, and on the paper towel a few grub-like drone be larvae, and some immature developing drone bee pupae with darkening eyes. I removed the single little red mite I found on one pupae and placed it on the paper towel to the right in the photo so you could see it. It looks like a shiny little reddish-brown bead with tiny legs.

When these varroa mites run rampant they can destroy a whole hive of bees. But if their population remains modest the bees have little trouble living with them.
My drone pupae examination was very encouraging! I needn't worry about combating mites at the moment. I put the thawed drone frames back in the hives where they had been. The worker bees will quickly clean out the dead pupae, repair the comb, and the queen will lay new drone eggs in it. I will now let the bees raise the next couple of batches of drones in peace. I'll probably check the mite levels again in about 6 weeks.

If there had been a lot of mites, I would start more regularly pulling and freezing those drone frames when they are capped, since that is where the varroa mite concentrates its breeding activity. Some beekeepers use this mite 'bait frame' method to keep mite populations under control instead of using miticide/pesticide applied inside the hive to kill the mites. I would much rather freeze some drone pupae than apply pesticides to my hives. The bees do raise additional drones on the edges of 'regular' brood frames anyway, so there will always be some drones in the hive to mate with nearby queens.
But for now, I can relax... my bees are doing well on their own.


  1. I'd much rather check for mites the way you did it. We were taught to use the sugar method, the alcohol method or the screen bottom board. I really wish I had that screen bottom board before I hived my bees. I don't want to do the alcohol method or sugar :(

    How often do you check for these mites? I was just going to do it once in the fall, would you suggest more often? The mites are attracted to the drone brood, correct? and then transfer onto the females later?

  2. Hi Michelle,
    you get a couple of 'drone frames- either the green plastic ones or just buy a 10-pack of drone sized wax foundation like I did.
    I would check at *least* twice a year- in summer and in Fall. Spring/summer/fall would be best I'd think.
    Yes, the mites prefer to breed in the larger drone pupae cells. You wait until the drone brood has been capped for a week or so. It is kind of an icky job, but better than using miticides.
    You can just CHECK for mites by opening some capped drone cells anywhere on the frames. But if you find a bunch of mites you can put in a whole special drone frame like I did, and use it as a place to lure the mites and then freeze-kill them periodically.
    Nothing will eliminate all of the mites, not even pesticide treatments, ...but monitoring their numbers and keeping the mite population down is important.

    I use open screen bottom board and upper entrances too, to keep good air circulation going.

  3. Thanks for the advice! It is very helpful!