Robber bees will rob another hive if the hive is weak or if there are drought conditions and there is a lack of nectar sources. Normally a hive that is being robbed is a weaker hive or is low in numbers and they are not able to fully defend themselves. Normally you will only see robbing in the fall time, going into winter when bees, yellow jackets and others are all looking for that last source of food before winter sets in. Yet with more frequent drought conditions and warmer temperatures we are now experiencing robbing in the spring and late summer as well.
Robbing normally happens in the fall but it can also happen in the spring or during times of drought. If the spring temperatures are very warm and there is not enough rain for plants to start blooming robbing can occur. So there was not nectar available and we saw some robbing within our hives in the early spring. Most of our hives are in rural areas where plants don't get watered like they do in a neighborhood or suburban area. When there is no rain, many bee plants and trees still get watered in suburban areas providing a nectar source for the bees. During the summer of 2012, Colorado also had a drought and again we saw lots of hives being robbed.View the video to see bees robbing a hive and what to do
Over time you will be able to tell if your hive is being robbed or if the activity you are seeing is something else, such as orientation flights of young bees or drones being kicked out in the fall.
In these scenarios you will see lots of activity at the front of the hive. Remember that robbing normally occurs during the fall, this is not a time you would be seeing orientation flights of young bees. But in the fall you would see some “wrestling” at the front of the hive when the drones are being kicked out.
This does not guarantee robbing, but if you see many fights happening on the landing board, on the ground at the front of the hive or bees hanging on the legs of intruder bees to remove them, this is one sign of robbing. Make sure it is worker bees fighting and not a worker bee and a drone who is being kicked out for the fall. If it is late summer you may see a large amount of dead bees on the ground in front of the hive. This can be an indication that there has been some fighting. Seeing dead bees during winter months at the front of the hive is normal, as the bees may not be able to carry the dead colony members in the cold temperatures. And you may still see this same pile of dead bees in the spring once the snow has melted.
Looking through the window you may see some bees that have slipped past the guards and they are scurrying to the back of the hive to get to the honey stores. Over time you will be able to distinguish this from the colony just being in a bustling mode due to a heavy nectar flow. Seeing bees fighting inside the hive is a sure sign of intrusion from another colony.
In this picture, with this large amount of cappings on the front of the hive, this hive has been taken over not only by robbers but a mouse as well. Robbers don't take their time to nicely uncap the honey stores as they are in a hurry to get out before being caught.
Chewed combs You may see combs that have jagged edges where it was once capped but chewed open by robbers.
If you look inside the hive you may see a large amount of wax cappings (crumbles) on the bottom of the hive floor.
If you suspect the hive is being robbed you want to stop the robbing right away! A hive can be robbed out of it's honey stores in a day if there are many colonies in the area that are robbing the hive. Also a top bar hive is smaller in volume and a larger Langstroth hive(s) or tree colonies in the area. Larger colonies can quickly take over a smaller colony of bees. To stop the robbing, you will want to reduce down the entrance of the hive so that the bees have less of an area to defend.
Screen mesh rolled up, tucked into the entrance, covering 3/4 of entrance
You can use screen mesh to cover part of the entrance of the hive. The screen mesh allows the hive to still get air flow and ventilation but also reduces down the size of the entrance.
You can also use grass or sticks to stuff in the entrance of the hive closing down most of the entrance area. If the robbing seems intense you can temporarily throw a wet sheet or towel over the entrance. You will only want to do this for a short time (10 minutes at a time) so your bees do not overheat! But this will stop the robbers abruptly until you can get some screen stapled over their entrance. The more they are being robbed, the more area you want to cover with screen on the entrance. You can always open it back up if needed
(This hive entrance also has a ¼ inch mouse guard on the front of the hive)
If a hive is really getting robbed out, sometimes robbers have found an additional opening into the hive. Check that there are not some top bars or spacers that have a gap between them. And check that bees are not able to get through the back of the hive
Always be careful when feeding a hive and always feed the bees with a dish inside the hive. Putting an open dish of honey outside the hive will attract bees and yellow jackets from all over. Even with the feeding dish inside the hive, the smell of open honey will be an attractant for others. (Read our Winter Feeding article) Consider closing off part of the entrance with screen mesh (if the bees have not propolised the entrance themselves) to reduce down the entrance.
If the hive has been robbed out and there is still a colony of bees, you will want to reduce down the entrance (with the screen) to an opening where only one or two bees can fit through. If you need to build them back up, carefully feed them (Read our Winter Feeding article) or combine them with a stronger hive.