Oxford Bees

Pests and Diseases

Very high Varroa count for city centre hives

Submitted by will on Fri, 19/04/2019 - 06:34

I did a 24 hour Varroa drop count yesterday. This involves clearing the removable hive floor and counting the Varroa mites which drop out of the hive over a 24 hour period.

I counted

  • 15 Varroa on the floor of Colony 12;
  • 16 Varroa on the floor of Colony 4;
  • 30 Varroa on the floor of Colony 8.

These are very high numbers of mites for this time of year.

The modelling referenced by the National Bee Unit suggests that colonies starting the year with this many mites will be overwhelmed during the season. I'm not going to treat. I'll see what happens.

I did try to insulate 2 of these 3 hives before winter. The uninsulated hive had 16 mites. There isn't a noticeable difference in mite numbers between insulated and uninsulated which is counter-intuitive -- warmer internal hive temperature should encourage brood rearing which should give opportunities for mites to breed. This is a very small sample but I'm not seeing that correlation here.

Varroa fall is worryingly high for Spring

Submitted by will on Sat, 13/04/2019 - 19:38

I have seen a worrying number of Varroa bodies on the floors of my hives. This is particularly concerning at the start of the season because it suggests much higher numbers of the mites later in the season. If I was a conventional bee keeper I would treat the hives now. I'm not going to. We'll see what happens.

I periodically look at the removable floors in my out apiary in town. I've seen Varroa bodies on the floor of all the 3 hives there. I haven't been able to count the rate of fall yet but there were enough bodies to be a concern. There are also Varroa bodies in my hive in Headington. This afternoon I cleaned the hive floor and, 4 hours later, found 2 new bodies. This rate of floor is alarming.

The hives which contain colonies 8 and 12 were insulated with cork last Autumn. It wasn't the best job ever but it might have raised the temperature of the inside the hive so that more brood were raised. This would provide a great opportunity for Varroa to breed through the winter. I don't have evidence whether the insulation worked. I will try to count mite numbers to see whether there is a clear difference between insulated and uninsulated colonies. Colony 01 is uninsulated and has the very high mite count. Confusing.

Around the start of April there were also piles of dead bees outside the front of my hives in central Oxford. These were not fresh. It wasn't clear whether they died in the hive and were dumped by undertaker bees during the cold weather, or whether they crawled out. Either way it's not good news. Colony 8 had more dead than colonies 4 or 12.

I don't know what these bees died from. There were non-flying bees outside the hive on the ground. They could be suffering from a paralysis virus. There were no obvious signs of Deformed Wing Virus. I just don't know and I'm not likely to find out now.

Drones emerging from Colony 1

Submitted by will on Sat, 30/03/2019 - 14:30

Today I've seen several drones around Colony 1. This shouldn't be a surprise. April is swarming season so colonies which are preparing to swarm will be rearing Queens.

The drones have fully formed wings but appear to be unable to fly. I've found a few just walking around. I threw them into the air but they didn't fly. They might be suffering from a paralysing virus.

Early drones may be more likely to be affected by Varroa infestation because there are fewer of drone larvae early in the season, and the Varroa viral load can be more concentrated.

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.

Wasps everywhere but none appear to be getting inside

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 there  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.

Varroa drop not quite zero

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.