Bee survival percentages

[voytech104]

Does anyone has similar data for Scotland ?

Date of hatch survive through the winter percentage

until 26 July - - 39%
between 27 july until 26 august " " 82%
between 27 august until 7 september " 88%
between 8 september until 18 september - " " 70%
between 19 september until 27 september - " " 41%
between 28 september until 8 october - " " 30%

[Adam]

Hi Voytech. Where did you get your data from?
39% before 26 July is pretty poor.

[gavin]

If that means 39% of the bees hatched in some period before 26th July will still be alive in spring, that sounds fine to me. I get the increasing percentage to early September, but why does it decrease after then?

[The Drone Ranger]

Voytech

I think its highly unlikely that any bee hatched in July other than a Queen would still be around in Spring.
No bees that become foragers could survive
Juvenile Hormone levels would be too low in July bees for the required lifespan

[gavin]

Maybe in the situation where a queen is shutting down laying early? An older queen or one in an environment where there is good spring and summer forage but conditions in autumn discourage more brood raising.

It does seem unlikely when bees are busy on late summer and autumn flows, and raising lots of brood on them too.

[Rosie]

If that means 39% of the bees hatched in some period before 26th July will still be alive in spring, that sounds fine to me. I get the increasing percentage to early September, but why does it decrease after then?

I wonder if it's because at the location where the tests were done the pollen quality was in decline. It could also be that by late September the nest was so small that almost every pupa had a varroa mite tucked in with it. We would have to know a lot about the conditions and location of the test to make sense of it. An interesting topic to study though.

Rosie

[Jon]

A couple of times I have had to open colonies in late October and have been surprised to find 5 or 6 frames of brood.
My queens usually slow down or stop in late August and then start up again with a vengeance in mid September when the Ivy starts.
I have always imagined the bees which overwinter are hatched in September and October. Pure speculation on my part but like DR, I don't see how bees hatched earlier are going to be around in spring.
I thought it was bees which never had to rear brood that lived longer, so the overwintering bees are pretty much the contents of the last brood nest

[The Drone Ranger]

These articles touch on both Jon and Rosie's points and although they don't quite answer the question they are interesting nevertheless.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2398712/

http://www.coloss.org/documents/wg3-workshop-honey-bee-colony-vitality-wageningen-30-june-2013-1-july-2011/at_download/file

Quote from the coloss.org doc :-

" Although beekeepers often do not like to treat their hives against V. destructor
during July, the period that they are most probably collecting honey, treating the bees before their transition to winter bees does increase their lifespan and thus increases their chances to survive winter.
Treating hives against Varroa in August or September results in lower lifespan of the winter bees than treating them in July, but a longer lifespan than not treating them at all"

This little snip sort of agrees with Eric MacArthur's view that formic acid early is the best way to treat varroa

Personally I am a bit windy where it comes to formic acid as "there's many a slip twixt cup and lip"
So I prefer the thymol in August/Sept route

[Calum]

Hi
latest teaching I received (July 2011) purported that the best method is to alternate (yearly) between lactic acid (a really fun way to treat) formic acid and thymol – in order to prevent resistance buildup. I have bees since 2007 and have always treated with formic (not keen on the thymol residues in wax) in aug-sept and oxalic in Dec have yet to lose a colony. In three treatments so far this year 600-1000 mites fallen so far (four doses 60% to got).
The proposal of treating in July is also just silly as it completely ignores reinvasion.

[The Drone Ranger]

Hi
In three treatments so far this year 600-1000 mites fallen so far (four doses 60% to got).
The proposal of treating in July is also just silly as it completely ignores reinvasion.

Calum
Were these treatments in August then ?
How many hives in the sample ?

[nemphlar]

I used FA thats formic acid this year for the first time. As I only had 4 surviving hives I thought I,d experiment on 1 hive only in case I managed get it wrong and wipe them out, I treated them 3rd July. The insulated eke along with the evaporator seemed to work ok and on 23rd I treated the other 3 hives
Just checked a 7 day natural bug count, the original test hive had 13 the 3 others had none. I dont have a lot of confidence in natural drop counts, but not to see any is curious

[The Drone Ranger]

Hi Nemphlar

I thought July was the recommended month for Formic

Just when Calum said it was silly because of re-invasion I thought he might be overlooking the killing of varroa in sealed brood.

Also I hear that there can be 10 - 20% of the open brood killed by the treatment so not something I would think for August and Sept you need the winter bees.

I am just guessing as I have only used formic a few times mainly because I like the smell of thymol :)

[nemphlar]

I think I'd agree DR. I didn't check pre or post treatment larvae count, but I did find some dead 3/5 day old larvae on the floor, assuming the bees dumped most of the dead out of the hive it's probably significant. If this were to happen in August,it ight be more difficult to recover. I still intend to use OA for winter. I think it was your data that showed zero natural drop prior to treatments, but still showed varroa after.

[Calum]

Hi
I am treating 30 hives. And my mentor has another 24 hives. We see about the same mite levels on 3 sites.
The reinvasion is a real problem, one of the institutes here set up a bee count on the entrances to hives in late Aug early Sept.
In one case they had more than 1000 bees entering the hive than left it on a days tally. The hive had not been robbed. Bees from other colonies that are collapsing will beg into other hives bringing their varroa with them.

Trying to get 5-7 treatments in starded first week August, every 5-7 days.. Fourth one done last friday. I use 60% formic acid, and try to treat when the temperature is below 25°C but above 18-20^C. I have not noticed any brood loss. When it has been too hot / the hives were unshaded I had that issue in the past, but the hives survived it.

[nemphlar]

Calum
Your running quite few hives for an amateur, do you think if you were able to treat them simultaneously it would make difference. Are all the hives in your area under your control

[Calum]

In the area I keep my bees there are a couple of hundred hives; in 2009 our club in Lindau had 49 beekeepers with 520 colonies.
There is another club in the town but they are not as big. Horbranz over the border in Austria about 5 km away also hs a club with about 30-40 beekeepers...
So not all hives in the area get treated at the same time, and there are always a couple of swarms that noone caught.

[nemphlar]

A bit more productive than our marginal west of Scotland then, had a wee look on google looks very nice

[Calum]

Big apple and pear growing area due to a really good micro climate around the lake..
Plenty of dandelion and clover between the tree rows, that is not constantly being mown for cattle feed, and plenty of mixed forest for 'wood' honey.. The varroa problem is immense though. the high density of colonies and some beekeepers that prefer to treat their bees once less instead of once more to save a few pence. The people in this area are renowned for having far deeper pockets and even shorter arms than even the Scots.

[The Drone Ranger]

Calum

have you tried using thymol instead ? it is acting over a longer period from each application so might take care of any new invaders .
I dont think it contaminates comb any more than Formic or Oxalic would

Thanks for the explanation by the way

[Calum]

Hi
I will probably give it a go next year just to give the varroa a different treat.
Oxalic and folic acids dissapate over time (they have from now till next may when I harvert). The oils in thymol build up in the wax apparently - I think that could become an issue if you always recycle your wax for frames or use exclusivley thymol.
I do treatments of 60% Formic acid 2ml / frame on a foam cloth from above. This method is only still recommended in Bavaria due to the need for a relativly high temps and low humidity. Long term treatment with 80-120ml 80% formic acid in a medicine bottle is more prevelant in the rest of germany and austria.