Monday, 13 July 2015

Tree Bee or not Tree Bee, that Was the Question . . .

Back in April we started hearing a strange noise at night from the bedroom and weren't sure what it was or where it was coming from. At first it was a fairly quiet muffled 'grunt' and sometimes quite gentle and dove-like. We have a thick climber growing at the corner of the house, I wondered whether a dove or some other bird was roosting there or even nesting and the sound was carrying through the grill. I looked, there wasn't.
At other times it was quite sniffy or grunty, almost hedgehog-like and next guess was a hedgehog nesting under or close to the bush in the thicker undergrowth. I looked, there wasn't.

As time went by the noises became louder, more animated and definitely more confusing, sometimes sounding like a troop of monkeys, and as it became louder it became obvious that it was coming from the attic, right in the corner of the room.
I investigated but couldn't see anything in the attic corner, (certainly no monkeys) though it isn't easy to see as we have deep-piled insulation and a narrow-angled roof.

The noises continued to grow louder, sometimes during the day but mostly through the night. I now feared we had rats up there after finding some info and similar sounds on the internet so decided a more thorough investigation was needed.
Back in the attic I went, with head-strap torch, garden tool for peeling back the insulation and poking around in corners, board to place over struts for kneeling on.
Again nothing, no horrid smells, no sign of any animal habitation or damage, and no noises until I heard a bzzzzzz and looked across to see a large bee crawling along the far wall. Couldn't be just bees could it?

That's a bee crawling up the wall just right of centre 
More investigations and though bees were more likely, I was still convinced rats were the culprit as by now the noises were like animals in communication with each other, sometimes softly, other times aggressive, though the aggressive noises were certainly more drill-like and bee-like, an aggravated series of buzzes. But the bees theory did solve one quandary as there had been a constant low-pitched hum which I thought was a fault with the heating, but thankfully that was definitely the bees.

It got to a point where I would end up sleeping on the settee rather than be kept awake all night by the ungodly noises as among other things I couldn't stand the thought of having rats scurrying about above my head while I slept.
We already had a nest of Tree Bumblebees in the garage roof and looking at the bees coming and going from under the eaves these were the same. I was up and down the ladders many more times with always the same result, each time poking around a bit more closely, each time finding only bees and nothing else.

A Tree Bumblebee Bombus hypnorum
A relative newcomer to our shores, first noted on the south coast in 2001 but rapidly spread northwards
and now present in southern Scotland
Eventually (after some weeks mind you) I concluded it was after all just the bees, literature on this particular species says cases like ours cause concern as the bees keep unsociable hours, and it's the chatter of the young Queens which make all the noise, but they should depart the nest in early July and the nest will die off and be abandoned shortly afterwards.
True to form the noises have all but abated now, just the muffled 'grunts' now and again of the resident Queen like back in April, and soon she will be away herself.

Usually the earliest species on the wing, a variable tawny thorax, black abdomen always tipped white.
Unlike other bunblebees they usually nest very high up, mostly holes in trees in the countryside.   


In urban areas they will take over nest boxes (even evicting birds)
but typically find their way into houses through holes under eaves and under roof tiles
(don't I know it)  

The workers feed on a variety of plants and are highly active. Nests in roofs are often made directly
on the back of plasterboard ceilings, making the noise of the 'hive' sound a lot louder
(don't I know it again)    

At first a nest will not be conspicuous, but tell-tale signs
are yellow pollen splodges around an entrance hole, and dead workers
on the ground outside a nest site. Dead bees are simply
dumped out of the nest hole. 

By the end of May activity around the nest starts to become conspicuous, as clouds of bees start to gather around the entrance to the nest in a behaviour called 'nest-surveillance'. 

This can look quite intimidating, but is in fact quite harmless, for these are drones, stingless males, dancing
around the nest hole waiting for the young queens to emerge for mating.
Observe them and you will notice they always face the nest in anticipation, and smaller worker bees will fly
through the swarm straight in and out of the hole as usual.
This behaviour lasts from dawn 'til dusk for a number of weeks, ours peaked at around 16 individuals but is now
down to 1 or 2. Once they leave the nest the drones don't go back, fending for themselves until they expire.  

And this is what it's all about, a lucky drone attaches itself to a larger virgin queen.

They grapple in mid-air and fall to the ground. It actually looks like they're fighting at first,
but once attached properly, mating can last for some time . . .

. . . and not always restricted to a twosome
Two males will sometimes clash and fall to the ground entangled. This is
 apparently erroneous mating but this poor bugger was left damaged
and crippled after one such clash.  

I got the information from :
http://www.treebee.org.uk/wp-content/uploads/2014/06/Tree_bee_article.pdf
It explains fully the behaviour and life-cycle I've witnessed over the last few months and put my mind at ease. The bees may have caused me some sleepless nights but at least I gained some insight and knowledge of another fascinating micro-creature.

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