Tag Archives: mite control

Survey mite assumptions & failed inventions

There is no selection in mite control for none as an answer it assumes all do mite control and I do not.
RESPONSE – We have a none for non-chemical treatment controls. Then a screen did you use a control – clicking none takes you past the specific controls to section 9 on queens. We do have another for all multiple answer choices and you can put none in there.

My bees are in a hard to feed area and I do well except in wintering. This year I moved them in to their bee house and failed to connect the entrance I invented with nosema and blocking the hive entrance. When I realized my mistake my hives were doomed to fail. Mostly my fault I should have 6 strong hives right now. I lost two hives in late September 15 airplane spray of some type then seven in January 16 I think five I killed with my invention 2 hard cold killed, I lost 2 in February march 16 hard cold snap week hive but one with brood and 3 frames of bees just died I think it should have made it.
Response – The main thing is to learn from the mistake – you had a good idea but it didn’t quite work out as intended. The losses you describe are too common for our area however so maybe it wasn’t just your management (or lack thereof) that was the issue. I trust this season will be different – at least the chance to make a different mistake with the bees.

“…mite control has no effect on survival!”

I’ve tried several different methods of mite control, feeding etc. and it has no effect on survival!

RESPONSE: Mites are a really tough pest to control.  You should be monitoring and use more than one control option. We have to mix up our options. Sorry you have not found the formula of what works best for you yet. Check out the Tools for Varroa Control on the Honey Bee Health Coalition websitewww.honeybeehealthcoaltion.org/varroa

Confusing sanitation question

I don’t understand the sanitation question (maybe the 3rd or 4th)

RESPONSE: thank you for your comment. Apiary site selection means we can reduce drifting and help our bees stay in their proper hives by how we site our hives in the apiary. I am working on further explanation to help better explain – I think we do too little on basic sanitation with our bees and that makes mites stronger and more of an issue in our high colony losses.

Early spring swarming altering counts?

On section 11: I wanted to reply 3-4 colonies, based on my current hives swarming. Went from 2-3 hives due to a swarm from one of my hives this April 2016. Questions about packages of bees vs. swarms of bees might be of use in terms of overwintering, Queen health and survival. With regard to varroa control, allowing for natural swarming to break the mite cycle might be an informative category. In terms of learning beekeeping, my best source has been the online Warre listserv. Might want to include such a category (yahoo groups) in your questions. Thanks so much for doing this! I look forward to seeing the results.

RESPONSE: That you for your comments although we do get at many of them within survey questions.  Allowing annual swarming might be a good response option to split out. I think online sources should be an option – will see about adding it & we do have category other which is where you would state this. We will transfer it from here this year.

Varroa mite control – what works ! By Dewey M. Caron

The pnwhoneybeesurvey received responses from 250 backyard beekeepers in 2015. Overall overwinter losses of individuals with either 8- or 10-frame Langstroth bee colonies was 27%; factoring in total backyarder losses for beekeepers entering winter with Langstroth, Top Bar, Warre, 5-frame nucs or other hive types was 29%. Our annual OSU survey of commercial and semi-commercial beekeepers (13 OR individuals maintaining some 60% of the estimated total colonies in the state) was 14.2%, somewhat below the commercial/semi-commercial beekeeper loss rate in the Pacific Northwest states of OR, WA and ID combined (=15.7%).The BIP national survey that included both backyarder and commercial beekeepers, reflecting survey responses from more backyard individuals but the majority of colonies were those of commercial beekeepers, reported a slightly lower overall loss of 23.2% . This is shown graphically as Figure 7 below.v1
Mite Monitoring
One hundred sixty three (163) individuals reported that they monitored for mites during some of the previous year (see pnwhoneybeesurvey.com for information on monitoring and when the monitoring was doneseparated by method of monitoring). The graph below shows the method used expressed as percent of individuals with number of individuals shown in ( ) within the graphic. One hundred individuals (37%) used sticky board mite drop, slightly over 100 (41% total) used visual inspections of either adult bees (54 individuals) or drone brood (55 individuals), while 45 individuals (17%) used sugar shake. Fourteen (14) individuals did an alcohol wash (5%) of total. The total is greater than 250 since
44% of responding individuals used more than one monitoring technique (both visual inspection methods were often checked for example).v2
We know the most reliable technique for examination of mite populations within a bee hive is via use of alcohol washing or powdered sugar shake. When we compared the individuals who used each technique (whether singly or in combination with another technique) and the reported loss by the same individuals, the result illustrates how significant monitoring with sugar shake was as this group had significantly lower overwintering losses (22%) compared to those who did not monitor (89 individuals – 31% loss) or used visual monitoring (29% and 31% loss rates -see graphic below). Those who checked sticky board also had significantly lower losses (22.5%). Individuals (14 total) who used alcohol washing did not show reduced losses, in part, because the variation among those 14 individuals was large.

Use of a Non-Chemical Control
We asked in the survey about control, both with a varroa control chemicals and via use of a non-chemical technique. In the options for non-chemical control, we received 406 responses from 75% of the individuals – 25% (49 individuals) did not indicate use of any of the choices nor fill in the other selection opportunity. Ninety-seven individuals (51%) ireported use of 2 (56 individuals) or 3 or more techniques (41 individuals). The graphic below shows the percent loss response for the alternatives offered, minus the 150 individuals (37%) of responses who checked use of screen bottom board (which is reported in a different report on the pnwhoneybeesurvey.com website – under Screen bottom boards.) Losses for each alternative are irregardless if they used only that technique alone or used it along with another/other methods.v4

There is no statistical difference between the data points. None were widely used. Individual selections varied from 49 individuals who checked nothing used to 21 individuals who said they used the technique of requeening. Numbers were relatively small and variation was large. The only value that was below the 27% average loss was use of small cell/natural comb (24% – most responses seemed to be the natural comb choice). Largest loss values were for requeening (36%) and brood cycle interruption (39%), the two techniques that are usually listed as viable, useful non-chemical controls. Why they are on the high end of the loss scale is unknown.
Chemical Control
For the users of 8 and 10 frame Langstroth hives, we compared the percent loss of individuals who used a chemical control for varroa mites (142 individuals) to those who did not. The loss rate of those using a chemical control were one-third as large as the overall group and were nearly double for those who did not use a chemical control. Results were statistically significant from the total loss of this group of 27%. v5
Examining individual choices (50 individuals reported use of more than one chemical) show use of three materials,resulted in significantly lower overwintering losses. Graph below. v6
Beekeepers have various options for Varroa control. The key to better overwintering is to monitor using sugar shake or alcohol wash to determine infestation level of a colony and then depending upon the season deciding on what might be an appropriate chemical or non-chemical technique to use to reduce mite populations. In this survey response we were unable to demonstrate the usefulness of non-chemical use to reduce overwintering losses. The BeeInformed Survey  2014-2015 preliminary results  does support our belief that non-chemical approaches can be useful and the Honey Bee Health Coalition website Tolls for Varroa Management guide Varroa management guide provides information on usefulness of an integrated non-chemical and chemical control approach to varroa mite population management.
Dewey M. Caron Sept 2015

To download a copy of this report click here

Screen Bottom Boards by Dewey M. Caron

Screen Bottom Boards (SBB) have a number of uses in our bee stewardship. They are widely substituted for a solid bottom board.  A 1939 Delaware beekeeper removed his solid bottom and left his colony open at the bottom, which he termed bottomless beekeeping. There truly is nothing “new” in our beekeeping practice of using a screened bottom on hives. Although many beekeepers use SBB to control varroa, BIP and PNW surveys clearly point out they are not a very effective varroa mite control tool.

In our national BIP surveys, fully 95% of respondents indicate they have modified the colony bottom board and now use a screen bottom board. sbb1 Our PNW Honey Bee Survey also asked respondents about screen bottom board use. Among Oregon and Washington hobbyist (backyarders or small-scale beekeepers), 79% of the 250 respondents said they used screened bottoms; 66% used them on all their hives with the remaining 13% using them on a percentage of their hives (See figure right).

Comparing overwinter loss percentage, there was no difference for the 21% who did not use SBB (27% loss rate , same as tsbb2he overall 250 respondent base) compared to the79% who did (25% middle column in left graphic  – column on right of graphic is overall loss rate for those beekeepers using either 8-frame or 10 frame Langstroth hives – when the data for individuals who used other hive types besides Langstroth is included, the overall overwinter loss rate for backyarders was 29%).

We also asked whether they blocked colony SBBs during the winter. The majority (51%) left them open over the winter period sbb3(never response). 19% sometimes blocked them and 31% said they closed them (always response) during the winter (see graphic right). When we examined winter losses for this response, there was no statistical dfference in loss, although the trend was for lower losses when the SBB were closed  (24% vs 31%).

As stated above, SBB are not an effective mite control tool, although most beekeepers state they are using them for that reason. In our PNW survey, respondent beekeepers who said they used bottom boards as a non-chemical treatment option for varroa mites, had no statistical improvement in survivability.  Langstroth 8-frame beekeepers who listed SBB use, entered winter with 97 colonies losing 25 by the spring (=25% loss rate) and Langstroth 10-frame beekeepers entered winter with 596 colonies of which 440 survived ( =26% loss rate); other hive types included in the survey (5-frame nucs, top bar hives or Warre hives) do not easily lend themselves to bottom modification with screening, although some individuals with such hives may use a partial bottom screen in place of a solid bottom.

With our Bee Informed National survey (www.beeinformed.org), use of SBB did not improve winter survival rate in any of our survey years when we directly compared their use with loss rates. However in survey year 2013-2014, northern beekeepers did have about a 10% decrease in losses when SBB were used compared to southern beekeepers. Experimental studies on SBB and mite population levels show either no or this slight ~10% improvement in reducing mite population levels when SBB are used.

So what can SBB do to benefit our bees?

Using a screen bottom aids greatly in hive ventilation. sbb4 It can be used with upper entrances at the covers or with ventilation ports added to hive bodies. Air circulation for better ventilation can be further aided by pushing the outer frames inward a bit to allow air circulation upward between the outer frame and box wall. Heavy burr and brace combs, sometimes due to incorrect bee spacing between the hive boxes, when both the bottom bar and the dropping of the top bars below the rim creates a ½ inch of larger space, and heavy propolis use in the fall, may reduce good air circulation in the boxes.

During winter, beekeepers at more northerly locations or higher elevations often close or reduce the screen opening beneath their colonies. It is not advisable to have wind blowing into the bottom of a winter colony but an air space beneath the colony, with screen bottom board left open, is not detrimental to colony wintering. The dead air space and moderating soil temperatures may be helpful. Often this dead space beneath a screened bottom can be created with hive stand configuration.

Another advantage of a screen bottom board is that it provides for a convenient garbage pit to remove debris and fallen mites from a colony. The original Langstroth hive had such a feature but it was discontinued when the hive construction was simplified. They were thought to promote wax moth with the design Langstroth used.

Screen Bottoms may offer some improvement for some beekeepers, particularly where winter confinement period is long and when mite populations are lower. In is not clear if this improvement is due to mites alone or to the other effects a screen vs closed bottom may have on colony survivability (see below). As regards varroa mites they should be considered a tool that may reduce winter losses when used in combination with other mite control treatments and tools.

August 2015 Dewey M. Caron

To download a copy of this report click here