Saturday, 11 July 2015

Tree Bumblebees at St. Catherine's, Windermere. BEEneficial Invaders?

Tree bumblebees (Bombus hypnorum) are native to Europe and were first recorded in the UK (New Forest area) in July 2001; they were probably blown across the English Channel. Since then they have spread rapidly with colonies spotted north of Carlisle.

They are tricoloured.. ginger abdomen..white tail.

As their name suggests they nest in holes in trees, but bird boxes appear to be their favourite places to set up home; a bird box has been taken over at St Catherine's.

Male tree bees are flying around the bird box waiting for the new queens to emerge. Male bees have no stings. They are harmless.

A closer look at four of the males vying for pole position; competition between them is intense as there are many more males than queens.

The worker bees can occasionally become aggressive if they perceive a threat to the nest. I got too close for their comfort and was stung! Unlike honey bees bumblebees do not have barbed stings. They are more like wasps and may live to sting another day.

Two years ago tree bees took up residence under the eaves of the staff toilet at St. Catherine's. These toilets were put out of use for a while as the doors opening and closing really irritated the bees; they made it obvious! Image © Ben Knipe. 

A worker tree bee with full 'pollen baskets' heading for the nest under the eaves. 
© Ben Knipe.

The entire colony dies out after a few months except for the new queens. They hibernate in Autumn emerging in Spring ready to start new colonies.

Tree bees are generally perceived as natural invaders. (Not introduced by humans). Most experts consider them as valuable additional pollinators and do not think they are a threat to the long established bumblebees in the UK.

Arguments to support this are that tree bees exist alongside several other species of bumblebees on the continent that are also found in the British Isles.

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