22 March 2013


On a rainy day all we can do is think about insects, this is the sort of weather that makes me wish I was into plants more!

As I said in my comment to Gareth's post of 19th here are some pictures and explanation about the bees mentioned. I also managed my own "oops" in the comment, the free abdomen is the gaster not the propodeum (this latter is attached to the thorax).

The bee on the Draba azoides is in my opinion Lasioglossum calceatum:

it has the hair bands on the gaster (abdomen) half showing through the transparent rear edge to the tergite (dorsal segment) in front (beware there are other species of Lasioglossum which can show this):
A check to Lasioglossum is the veins shown below meeting at 90 degrees (at point V, other genera also show this, clicking on the pictures will make them much larger):
 As you can see the Andrena wing below has the veins meeting at an acute angle at V (there are Andrena species as small as Lasioglossum!):
In the case of the females an additional check for Lasioglossum is the presence of this trench (rima) at the tip of the gaster, sting would not be showing in life!:
 Here are both sexes of Andrena flavipes (sorry about the sex Barry):
Hope this is helpful. Much more can be found on the excellent BWARS website including a free downloadable book on bees which will allow you to identify all the genera.


Barry Stewart said...

Nice lesson Ian - it's time someone brought out a visual key that works as well as you've just explained.
I'm guessing the male is on the left!

gareth thomas said...

Yes - nice one Ian. Below is a copy of the comment I just put under my blog of 19th.

Been back to the original files - taken, remarkably, on 19th March last year, same day as 2013 blog by coincidence.
In better pix of the bee, the white hair fringes are unmistakeable and on one there is a wing-shot which shows that vein at right angles, not acute.
So, correction confirmed. Well done, you have passed the test I set you with honours! Thanks.