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What could be happening? 

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Total Posts: 10

Joined 2013-06-18

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I have Bombus Hypnorum nesting in the bird box in the garden. Today, I found three bumblebees that were dismembered. One’s head had come away (and it was sitting a few milimetres from their body) and soon after found another one that was missing their abdomen (again, nearby).  Another’s leg was sitting next their body.
All in all I found about 6/7 dead bumblebees, 3 of which had been dismembered in some way.

Are ants chewing up my dead bumblebees?

     
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Total Posts: 17

Joined 2013-07-05

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Could be wasps.

http://nurturing-nature.co.uk/gardening-for-wildlife/wasp-attacking-and-killing-honey-bee-next-to-bust-hives/

Birds also do this.

Although the article relates to wasps killing honeybees, I would think the same could happen to bumble bees.

     
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Total Posts: 216

Joined 2012-05-24

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Hi Alice,

I’ve had colonies of Tree Bumblebees in my garden over several years now.
They are located in a bird box high up on a wall, with covered water butts underneath.
Most days I find one or two dead bumblebees around beneath the nestbox; also sometimes disabled B. hypnorum drones crawling around in this area with one wing looking as though it is dislocated.

So, I suspect a local wasp colony has discovered the free corpses beneath your bumblebee colony and are dismembering the corpses.
I’ve also seen them dismember a BB that was sleeping out in a Vipers Bugloss plant.  All that was left afterwards were legs and wings.
The main target is usually the thorax, which is full of meaty muscles !

Could this fit with what you are observing ?

Clive

     
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Total Posts: 10

Joined 2013-06-18

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It could fit, but the thing is I never see wasps in my garden and I certainly haven’t seen them attacking any of my bumblebees, so while that could be the cause I don’t think it is.
I once found a dead bumblebee covered in ants in the garden, and they had chewed into his body.
I was also playing with the idea that the bumblebees could chew up the dead ones and remove them from the nest bit by bit, but since the dismembered pieces were so close together, it doesn’t seem likely.

Curious grin

     
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Total Posts: 216

Joined 2012-05-24

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Hi again Alice,

I’m attaching some photos showing a wasp predated bumblebee (B. terrestris/lucorum) that made the mistake of using the same overnight sleeping position in a Vipers Bugloss plant.
In the last photo the remains of the bee are partly obscured by a shed flower petal that had settled on the bee’s leg and then got stuck.

Clive

     

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Total Posts: 10

Joined 2013-06-18

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Oh, dear. He is very mangled.
The bumblebees that I found weren’t in any similar state to that poor fellow.
I have looked into the diets of ants and they will eat insects, so I am quite sure that is what’s going on. It seems they’re scavenging grin