Scotch Thistle Cut-back
Late this afternoon, I was cutting back the tall Scotch Thistle plants which have sprung up on recently disturbed ground. I've watched them grow, not in hurry to cut until they have put much of their effort into producing long, tall, healthy stems and leaves.
Then the buds start coming. Just on the crown heads first, then some of the laterals. It's just as the buds open into that beautiful purple floret that I like to cut back, using hand shears. I chop the heads off first, then gradually cut down the stems into small pieces, so that any buds just opening don't have enough nutrients in the cut stems and leaves to produce seeds. They will send up small stems from the roots soon, and in a last-ditch effort to reproduce, will form small flowers towards the end of summer. Hopefully these will not be fertilised and make viable seeds.
It was evening and the light level quite low, only just in time to get a reasonable picture.
HTC Wildfire Smart Phone, about 2 years old. Obviously there was a relatively long exposure time which amplified my slight camera-shake. The evening light has little red in it, so the flowers appear much more blue than their natural purple.
During the afternoon, I had cut back most of the thistles. However, there were numerous Bumble Bees flying around and supping nectar from the thistle flower heads.
Bumble Bees are not native to Tasmania. There seem to be few natural predators, and they have proliferated. Thistles are one of their favourites and the thistles obviously appreciate their attention! Even though the Bumble Bees can be seen as something of a pest, I still think they are busy little things, entitled to their short lives and a little enjoyment of their mealtimes. So, I left one plant uncut until evening, thinking that would allow the bees to go off home in due course.
At least 3 of the little critters didn't think so! They were still there on my return.
What do I do now?
Three Bumble Bees had gone to sleep on the flower heads. The air temperature was decidely getting cold. This is mid-summer here in Tasmania. I am 450 metres (almost 1500ft) elevation, and it can get cold at any time of the year. The latitude here is about 45 degrees south.
I have decided to wait until tomorrow when the warming temperature will wake the bees up and they can go off somewhere else for breakfast. Then I will cut the plant down.
Early Morning Post Script
At about 6.30am I went and had a look - there were still the three original Bumble Bees there, totally dormant. The air temperature was 59F (14C).
One hour later, the temperature had dropped to 50F (10C) and one of the bees was wearily trying to gather just a little nectar from the flower head, damp from the morning dew.
I had to leave then, and presume they took flight when the temperature was somewhere near to 70F (21C). Will check again tonight and tomorrow. Later in the day I counted 8 bees all congregating on those few flowers.
Calling other opinions
Has anyone else seen this behavior of Bumble Bees?