Dead Colony Forensics by Dewey M. Caron

About a dozen brave individuals gathered at the Zenger apiary colonies Sunday April 15th, during a steady Oregon liquid “sunshine” rain for dead colony forensics with Dewey.  Photo right by Mandy Shaw.

Temperature was low 50’s, with only a couple foraging bees venturing forth from 4 of 8 colonies. We hefted boxes and did autopsy on two dead-outs.

Bees die overwinter for a number of reasons. By doing a dead colony autopsy we seek to determine what might have been the likely reason for non-survivorship.  Understanding the why might help us avoid a repeat this next winter.

The first dead-out we looked at (photo above) proved to be a tough diagnosis.

The colony was a mid-May nuc donation from Beetanical apiaries of Lane Co. Hive had a standard and a shallow. The shallow frames were quite full (>3/4ths of cells) with capped honey. The shallow was lifted off and placed on upside-down cover.  There were dead brood remains on three frames of the lower standard box plus a small (<2000) number of dead adult bees on the screen bottom board and outside the entrance. Two adjacent frames had widely scattered capped brood cells extending in an oval  covering over  1/3 of the middle of the frames; there was a fist-sized patch of compact capped brood but it was not contiguous with the scattered brood of the other two frames. There was no evidence of a dead cluster but a considerable number of cells of stored pollen on 5 frames. Ample mold was evident in pollen cells and as a powdery grayish mold on surface of cells. Colony was sampled for mites with a sugar roll in September and had only 2 mites (<1%).  It was NOT treated for mites as it was a non-treatment control. Colony was alive in a mid-October inspection.

Photo of the three frames with brood shows the frame with a patch of compact brood (held  in my right hand) and two frames with very scattered brood (one in my left hand and the third on top of adjacent hive; this frame is shown isolated in photo right). Full super on ground.   Photos by Deb Caron.

So what can we diagnose? Lots of honey and pollen stores so we can likely rules out starvation. Small number of dead bee bodies suggests a small colony but if we would believe death from a too-small population of adults, there should have been evidence of a cluster with bees within cells and dead bee remains on the frame(s).  There wasn’t.

Thus our best guess is a colony that had a BEE PMS condition. The scattered brood remains on both sides of the two frames suggests this –a spotty (snot) brood situation MIGHT have been diagnosed in the October examination, but this requires a close examination of the brood; we might have noticed evidence to too few adult bees to cover the brood – both are subtle clues. The fist-sized brood area,  one frame over from the other two frames with scattered brood, might have been bees trying to escape the high mite numbers and their unhealthy brood of the 2 frames with scattered cells. Adult bees were likely dying prematurely and abandoning their (unhealthy) hive, thus the reason we saw only a smallish number of adult dead bees. The colony likely failed to rear sufficient fat, fall bees. The colony probably died within a month after the last October inspection, probably from a virus epidemic related to the mite infestation. NOTE: The September mite sample is misleading/confusing (we would expect it to have been higher); if an additional sample was taken it would perhaps have been higher?

The second dead-out was a more standard necropsy. Hive was a spring split,that struggled all season. It had 2 shallows. Colony had a 19 mite count (6%+) in September and was treated with 2 formic pads between the two boxes. It was alive in March (this spring) but noted as small. It was fed dry sugar on paper (some still remaining) and provided with a frame of sugar candy.

Opening the top and removing moisture trap, (all Zenger hives had moisture quilt traps at top) showed a dead cluster of adult bees on 3 frames in top box at top of the box extending down about ½ way on the 3 frames (see photos; in photo right, hive tool is showing the remaining dry sugar on paper – quilt trap with wood shaving lower right). The adult bees were black and showed excessive moisture; there were many maggots (scavenger fly) feeding on the dead bees. There was capped brood in compact pattern within the cluster. Dead adult population was small (perhaps 8-10,000 bees). There was NO capped honey in any of the frames of either box. Lower box was empty. There were some dead bees on solid bottom board. There was little mold.

So what was diagnosis? The dead cluster is characteristic of a colony that overwintered the tough months (Dec-Feb) and moisture of adult bees, maggots and little mold suggests recent death. The compact brood shows the colony was starting to expand in the spring (flight was noted in March). Although dry sugar (as candy and crystal sugar) was given as emergency feed (hefting would have revealed lack of enough stores), it turned out to not be enough — colony likely starved. Bee cluster too small to generate enough heat to make slurry out of dry sugar or candy so bees couldn’t use it. Photo below shows one of three frames. We see “bee butts” under the dead cluster and compact capped brood.  Photo by Deb Caron.

All frames, except one with high number of drone cells, could be reused for anew colony installation (package, swarm, split). Brush off dead cluster and from bottom board. If inclined wash mold with bleach or vinegar solution.

Living Close to the Edge

February in the Pacific Northwest Colony by Dewey M. Caron

February is a “pivotal” month for PNW bees. Queens have started laying eggs, especially those less than a year old. Our generally warmer winter weather in January, has enabled the workers of colonies with larger populations to expand the cluster size, opening up more cells for queen egg laying than might be considered “normal”.  This defines February as pivotal because colonies are often living “close to the edge”.

There is an adult age imbalance with more older than younger bees because the Fat bees reared in the fall are now senior citizens.  As the weather permits flight, these aging bees use body resources quickly. Fresh pollen to the February hive is highly stimulatory and important to rear critical replacements for dying adults. Unfortunately such expansion, along with the aging bees and clusters in the top brood box, mean less hive flexibility to quickly adjust to changing weather. Colonies less frugal with adult and stored food resources lead to the possibility of failure to survive in the coming two months. Underpopulated colonies, trying to keep expanded brood nests warm, can be lost in a cold, wet weather spell.

Our PNW Loss/Survivorship Survey is also at a “pivotal” junction. This fifth year of data will enable an official analysis of trends and correlations of losses to weather variation. Won’t you join us this year and share your overwintering loss/successes and answer a few questions about your overwintering and mite management? The PNW HONEY BEE SURVEY included over 350 respondents last year. It is simple to fill out. It is available online at pnwhoneybeesurvey.com/survey. We have the website open and ready for your survey responses in April. If you have been looking at your colonies and want to make notes to make filling out the April survey a breeze download the PDF note sheet at  pnwhoneybeesurvey.com/notesheet/.

 

Download this post as a PDF here

Survey & Club affiliation

TWO similar comments –
A- I am not a member of Willamette Valley Bee Association. I accidentally checked it and it wouldn’t uncheck. Using my phone, which is not ideal. Only affiliated with PUB and OSU Master Beeks program.”
B-“Some questions (radio button?) won’t let you remove a response if you’ve incorrectly marked it. It will move through the options, but won’t clear.

RESPONSE – This was an unforeseen bug that goes with the club expansion. In previous years we asked a participants club affiliation and many were troubled that they could only select one. Until we have the manpower to do behind the scenes web development, we are stuck with the options and minor programming that the Google form will allow us to do. Noting the error in the comments like you have done is sufficient for us to correct the error on our end so that it does not affect the reports. Thank you for bringing it to our attention and submitting your correction.

Colony failure & record keeping copy

Swarm hive was going strong when I left for Europe mid Oct to mid Nov. When returning there was not one bee, dead or otherwise in the hive. There were a few capped cells with normal bees not yet hatched. Lots of honey storage left. My first hive(2012) was doing fine Jan 7, heavy boxes, lots of bees coming and going on nice days, by Feb 24 there (and still is) are only a few bees left (baseball size cluster), including the queen, but no eggs. The screened bottom board was covered with dead bees on Feb 25 when I could finally get in the hive to see what was going on. I am assuming it is varroa mite, as the frames looked like the one you showed at WVBA during your presentation. The varroa count was low last summer in all hives, so didn’t treat. As a suggestion, it would be nice if we could print this document, so we have a copy of our survey as well. I tried to print this but would only print current page.
RESPONSE – Spring bee colony losses are “normal” for keeping bees – this is when we see colonies die. Varroa is always a good culprit to use when trying to diagnose a bee loss. I did offer paper copies at the WVBA meeting. The reason you could only print a single page is because the survey has “hidden” pages (when do or don’t pop up depending upon your entry response to that section). I recognize it is inconvenient to have only a single page – ask me if we have developed the way to provide this next year and if not you are welcome to use the paper mail in version next season taking a copy for your records prior.

Bee Stewardship

I keep my bees covered from the rain and off the ground with blocks and a piece of plywood on top of the blocks. I also shade from the direct sun in the summer.
RESPONSE – Both are good bee stewardship – thanks for sharing.

Swarms

At this time I have had 8 swarms as of 4/7/16. I have caught 5. While out of town I call others to come and they got 2. The 8th seemed to know where they were going and escaped successfully. I now have 10 hives.
RESPONSE- sounds like a lot of swarms. Some years the bees just want to reproduce

Overcrowed in spring

Treated my two hives with Oxalic acid on January 10th- 55 degrees day. It was so warm early that my main hive was overcrowded by March. I did a split on April 2 and added a queen cell from a local breeder. Doing well as of April 27th Captured 2 swarms on: April 1st, 2016-viable and doing well as of April 27th, 2016 April 10th, 2016-added mature swarm cells on April 20th from main hive to this queenless swarm. Still active but watching for signs that the cell formed a viable queen and she mated. I have not checked since we have had cold rain for the last 3 days with plunging nighttime temperatures. Feeding syrup

RESPONSE  – Mid April for queen mating is iffy some years. With queen cell requeening we should have positive signs (eggs at least) within two weeks, three at most. If beyond that then it might be best to combine (if there are enough bees to make it worthwhile). Thanks for sharing – hope that requeening event went well like the earlier one.

Hive loss results

Send results and analysis about why I lost my hives

Response – We will send  although it will take a bit of time for analysis as we are something near 300 responses this season. Appreciate your and all others who did respond.

Feral hive transfer

I lost a hive that came from my neighbor’s feral hive that was in a barn for years. That hive also died out in March 2016
RESPONSE: Sometimes we see bees doing well on their own – even persisting for years but then they don’t do well when we seek to transfer them and keep them conventionally. The study of Tom Seeley found that bees in tree hollows are different with respect to handling mites than our beekeeper colonies when we keep them at a higher density in one apiary. Thank you for your comment. Dewey

Costly hobby

It has been very costly for us on our farm- losing all 6 hives and having to replace them- but we have made a substantial investment in woodenware, time taking the classes etc……we’re all in, but this is difficult.
Response – Loss of 6 hives is indeed heavy. And you are certainly correct that it is a significant loss of time and money. I trust with restarts, if you elect to do so, the loss rate will be reduced this year. Best of luck with them. Thanks for your comment.