Oxford Bees

Pests and Diseases

Wasps overwhelming Colony 11

Submitted by will on Thu, 30/08/2018 - 12:03

Two weeks have passed since I declared that there was 'no drama'. Today Colony 11 is under severe pressure from wasp attack. Today there were maybe 3 or 4 wasps using the entrance for every bee. Inside there were far fewer bees than I would have expected and there was less honey. On the floor of the hive were a great many severed bee legs.

I removed the top 2 supers which were superfluous. I put a piece of thick paper over the hive entrance which seemed to stop the approach of the wasps -- at least for the moment. I am considering moving the hive as soon as possible.

Wax Moth!

Submitted by will on Wed, 22/08/2018 - 21:25

Today I earned the exclamation mark! I found the largest infestation of Wax Moth that I've ever seen.

It was my own fault, of course. I had left a stack of brood comb on my workbench and forgotten about it. I found it today a day or two after the larvae had woven their cocoons but before pupation had properly begun. There was a lump of cocoons half as big as my fist.

There were hundreds of larvae and cocoons. I had left the combs on top of some tools and a hive part. The cocoons were everywhere. I had to pick them out of frame grooves; around a hanging ruler; from inside a wood plane; and from off the bench top. Wherever there was a hole or covered area there were cocoons.

We keep chickens. Chickens love live food and they are very attentive when you give them wax moth larvae. I spent at least half an hour picking the larvae and cocoons off stuff from my shed. They spent a little bit longer extracting the larvae. I won't say that it was good work but the timing was lucky and the chickens were happy. Things could have been worse.

Submitted by will on Sun, 05/08/2018 - 06:36

My hives are surrounded by at least half a dozen wasps which want to rob them. They zig-zag in front of the entrance; they crawl in under the Varroa screen; they wait at the edges and drink from the water tray. They want the honey but they can't get in.

All of the hives in central Oxford have small doors and strong guards. Three of the four have at least 20 bees visible on the outside of the hive entrance. One hive had fewer visible but appeared to be just as effective at guarding.

Having so many Wasps around makes it hard to open the hives. Once robbers get in they are more likely to return. They're as happy to gain entry from the roof as through the door. I think that they're also more likely to successfully return and re-enter the hive because they smell of the honey from that hive. Robbing can become a storm which only abates when the hive is moved out of range of the robbers. That's a lot of work just for a look inside.

Robbers notwithstanding, I took a very quick look inside the hives in central Oxford to check that none had run out of space. They all have sufficient space for the moment. They are also all dropping pollen, which suggests they're still laying and thereĀ  is forage for them. There is plenty of door activity at all the hives. I found no Varroa mites on the base board. I was some evidence of Wax Moth and some evidence of new comb.

Colony 1 in Headington is also faring well. There are some wasps, but fewer than in central Oxford. There is pollen being dropped and plenty of door activity.

Submitted by will on Wed, 13/06/2018 - 07:18

Colony 13 is dropping Varroa. They are also cleaning out old comb so there is a lot of debris on the hive floor. I found 2 or maybe 3 Varroa bodies.

This colony is new to my apiary, having been established elsewhere. I haven't really included it in my Varroa Zero post because it's new. Hives D and G are included. There were no Varroa on the floor of either this morning. There doesn't appear to much activity in Hive D at all. I shall have to check them.

Varroa drop zero

Submitted by will on Tue, 12/06/2018 - 05:50

I regularly examine the floors of my hives. The stuff which falls out of the hive tells a story about what the bees are doing. I always look for Varroa mites. I've found none on the floors of any of my hives for several weeks. I don't know why.

Mites on the hive floor can indicate how many mites are living in the colony. Varroa live for between 27 days to about 5 months (source: Managing Varroa, National Bee Unit, 2017). The mites require bee brood to reproduce so it's not surprising that there are fewer mites in the early part of the year. What is surprising is that I'm finding no dead Varroa at all in well established and very active hives.

We had difficult weather in spring. The temperature started to warm and then fell dramatically. This led to a number of colonies dying of complete starvation or isolation starvation. Dead colonies don't support Varroa. Live colonies do, but only in cells with brood. I wonder whether this has interrupted the mite life-cycle and knocked them back. I do not expect to find any colonies where Varroa are entirely absent.

I have 6 occupied hives. Three of these are new colonies. I expect to have lower drop anyway because they arrive only with those Varroa which cling on to swarming bees (during the phoretic part of mite life cycle). I have one established hive where there is an Ant infestation. It's possible that the Ants are taking away the mite bodies. That leaves two established colonies which have brood but are dropping no mites. That's a small number of hives, but striking anyway.

There will be more to say about this later.

Anti-Ant (Part 1)

Submitted by will on Tue, 05/06/2018 - 20:37
Pine Tar (branded as Stockholm Poultry Tar)

Colony 01 has an infestation of black Ants.

I find hundreds of them on the base board. I find very little pollen and no Varroa. I think that they harvest these. I don't know whether they're a serious pest but I would expect to find them throughout the hive. In any case, the base board is the place where I do most of my inspections so I need it to be intact. At the moment it's being reorganised by the Ants.

My solution is to apply Pine Tar (branded as Poultry Stockholm Tar) to the legs of the hive. I've heard that Ants sometimes create nests inside the hive but I haven't seen any in there when I looked earlier in the season. I think that they're entering via the legs.

Poultry Stockholm Tar stays wet but sticky. I don't expect it to affect the bees because it's outside the hive. I will report back.

No crawling bees outside Hive A

Submitted by will on Mon, 07/05/2018 - 07:19

For at least the last 2 years there have been flightless bees crawling around outside Hive A. These bees were clearly suffering from Deformed Wing Virus or another disabling virus. This year there are none.

The cause was explained to me by a researcher at University of Salford. All winter the Varroa mites feed from worker bees. They accumulate DWV virus particles. In spring, when brood production increases they rush in to infest the new brood and transfer more virus to them. These bees show visible signs of DWV -- deformed wings or an inability to fly.

The absence of crawling bees can be explained in several possible ways.

  1. There are fewer Varroa mites in the hive. I usually check this by looking at the removable floor of the hive. I've found dozens of ants on the floor so I don't know whether they've been taking the Mite bodies away. I don't think that this is what's happening.
  2. The overall number of virus particles has fallen in the hive. It was very cold in April this year. This should have stopped the bees rearing brood. Virus is removed from the hive by bees or mites leaving the hive. If more mites died during April then it might explain some of the reduction.
  3. There are fewer brood this year. This seems most likely. The activity at the hive entrance is quite slow. I did look inside the hive and found only one frame of brood which was capped. I may have overlooked uncapped brood but it points to there being fewer bees and fewer brood. They're taking longer to build up this spring.

On reflection I think that Colony 01 is smaller this year which would mostly explain the absence of crawling bees.

The value of a feral colony

Submitted by will on Fri, 30/03/2018 - 19:13

People value things more when other people value them. Price is a useful proxy for judging what other people value, but price reflects usefulness and abundance and status and cultural history.

It takes experience and time to learn the value of that which is abundant, cheap or free. It takes no time to be influenced by someone.

I value feral bee colonies. Established feral colonies are where natural selection is allowed to happen. Established feral colonies are survivors.

Bee Keepers in England have valued the Italian strains for decades, particularly those which were selectively bred from 'Italian' stock at Buckfast Abbey: the Buckfast Bee. Professional and mainstream bee keepers value the Buckfast Bee because it is easy to manage and produces lots of honey. It's a product of modern agricultural thinking.

Honey bees now face new challenges: new invasive species; new pests; invigorated diseases; changing land use leading to less forage, or seasonal variability in the amounts of forage; new pesticides.

The Varroa mite is a significant challenge. It is a pest which was in balance with its' original host, the Asian Honey Bee (Apis Cerana). The move to the Western Honey Bee (Apis Mellifera) changed the mite's life-cycle so that it now infests worker brood as well as Drone. This has increased its' virulence. The mite has also super-charged existing viral diseases -- particularly Deformed Wing Virus which is implicated in the increasing number of failing colonies (Colony Collapse Disorder). The Varroa mite is a parasite which is out of balance with its' host, the Western Honey Bee.

The popular Buckfast Bee does not cope well with Varroa.

Feral colonies are probably either descended from, or related to Buckfasts. What sets ferals apart is that they have interbred freely and been subject to natural selection. Newly escaped colonies which cannot cope with the new challenges will die within 2 or 3 seasons. My best survivor colonies have been untreated for at least 5 seasons.

Oxfordshire is unlikely to be the place where Western Honey Bees evolve a resistance to Varroa. Evolution is not that convenient. Oxfordshire can be a place where natural selection is allowed so that the bees can reach a survivable balance with Varroa. My low intervention approach is intended to support that.

Anticipating a balancing of the host-parasite relationship

Submitted by will on Thu, 25/05/2017 - 19:40

Parasites rely on another organism for aspects of their feeding and/or reproduction. Whilst parasitism is a complex subject, the relationship between Western Honey Bees and Varroa mites is relatively simple. The mites live entirely with and on the bees. Food, reproduction and transport is all provided by bees. In this case, if the host dies so does the parasite.

Some parasites have periods where they are hosted by a different organism - for example Influenza or Malaria. Some parasites have long lived dormant phases - for example Anthrax. These can fatally damage their hosts without killing themselves. Anthrax depends on killing its' host so that decay releases it from the body cavity. Varroa is not like this.

Until recently I have been looking for an increase in the tolerance or resistance of bees to Varroa and its' diseases. I now see that the virulence of the mite should also decrease. This will bring the relationship into a balance where the parasite will not kill itself by killing its' host.

The Varroa mite became much more virulent when they crossed to the Western Honey Bee (Apis Mellifera) from the Eastern Honey Bee (Apis Cerana). It started to infect worker brood, rather than just drone brood. This gave it many more opportunities to reproduce and so overwhelm colonies. I don't expect the Varroa to stop infecting worker brood, but I do expect some change in the rate of reproduction or the effectiveness of viral infection.

My untreated hives have survived for extended periods without suffering Colony Collapse Disorder. Maybe collapsing colonies are subject to multiple stresses: Varroa plus intensive apiculture and/or another disease. I don't see evidence of resistance but I do see tolerance and patterns of disease expression which don't have significant effects on the colony.