Confusing Little Green Bees (Augochlorini)

IMG_1496I love me some little green bees!  I have posted about our Halictid friends, the Agapostemon before (and their nesting aggregations), but there are other little green sweat bees.  These, however, are much more difficult to identify to species.

What *are* you? (Aside from beautiful?)

What *are* you? (Aside from beautiful?)

In particular, there are three common genera that look very similar, even under a microscrope.  These are Augochlora, Augochloropsis, and Augochlorella.  Together, they make up the tribe Augochlorini.  All three live in my area and all three are about the same size, with overlapping colour variation.  How to tell them apart then?  Diagnostic characters!

For example, Augochloropsis has a D-shaped tegula (that’s the cover over the base of the wing), while Augochlora and Augochlorella have oval shaped tegulas.

D-shaped (left) versus oval (right) tegulas.  from Discoverlife.org

D-shaped (left) versus oval (right) tegulas. from Discoverlife.org

If you have a female (like the one above) if it is not Augochloropsis, it may be Augochlora if the marginal cell is squared off, or Augochlorella if the marginal cell is pointed.

The marginal cell looks squared off to me.  Can't see it?  Let's zoom in.

The marginal cell looks squared off to me. Can’t see it? Let’s zoom in.

I outlined the veins in red and circled the marginal cell.  See it now?

I outlined the veins in red and circled the marginal cell. See it now?

That suggests Augochlora.  To confirm, we should look at the paraocular area, if possible.  In Augochlora, it has a little rounded knob that extends down over the clypeus.

Hard to tell from this photo, which is not as sharp as I would like, but I think you can see the rounded knob.

Hard to tell from this photo, which is not as sharp as I would like, but I think you can see the rounded knob.  Let’s zoom in.

The paraocular knob is outlined in red and the region of interest is circled.

The paraocular knob is outlined in red and the region of interest is circled.

To me, this suggests that it is Augochlora!  And since there is only one species in this genus in my region, I deem it Augochlora pura.

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12 thoughts on “Confusing Little Green Bees (Augochlorini)

  1. Oh this so proves my point. How you guys do it is beyond me when so many look exactly the same but just a bit different somewhere on the tiny body. I read that some insects need to be under the microscope for proper ID and that must mean they are dead and pinned. I am going to have to enlarge my photos next time I see a metallic bee now. BTW, I think they are pretty. The color and reflected color is amazing.

    • They are really gorgeous! Haha you are right, this does prove your point. Yes, there are many species that are only distinguishable under a scope. With Lasioglossum, there is literally only one person on earth who can identify the males to species. And then there are the species that cannot be resolved at all because their characters overlap. *sigh*

  2. Pingback: Males are not useless | standingoutinmyfield

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