19 March 2013

Bombylius discolor/Andrena flavipes

On a similar subject to that preceding, these are some things to look out for in the next month on the Gower coast.
The Dotted Beefly, Bombylius discolor is not uncommon on the coast, for its main host appears to be the mining bee, Andrena flavipes.
Otherwise it is very uncommon throughout the rest of the British Isles.
Gravid females coat their eggs in sand and flick their eggs into the nests of these mining bees, where the larvae develop to parasitise the bees or their larvae.
They are easily distinguished from the very common B. major, which also occurs here, by the obvious spots on the wings (though a photo may be needed for this)

A. flavipes is one of the earlier mining bees around and may be located on some of the few flowers available in March, such as Draba aizoides, a very rare speciality of the Gower coast. These photos were taken around this time last year above Ramsgrove, Rhossili, when we had our 'Summer!'
However, I am reliably corrected that this bee on the Draba is Lasioglossum calceatum, another early ground-nesting solitary bee which may also be parasitised by the Beefly.


i.f.tew said...

Dear Gareth,

afraid the insect on the Draba azoides is Lasioglossum calceatum as far as I can see it has the very characteristic white hair bands on the propodeum (abdomen) which are half covered over by the see through cuticle of the tergite in front giving the appearance of a pink and white double band. I will post a picture of each tomorrow or try the bwars website as an alternative:

gareth thomas said...

Thanks I.F.T. for the correction. I was mis-informed. I have updated the blog. I understand that this Beefly is fairly catholic in its selection of hosts and any ground- nesters around at the right time can be chosen. From choice various Andrena species are favourites.

gareth thomas said...

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.