Found Syrphid at Trent - Eristalis (Eoseristalis)

Today I found a Syrphid in a closed hallway here at school.  I collected it in a vial and put it in the refrigerator for a minute or two to cool it down and take some photos.

Using the Syrphid key that I received at the pollinator identification course last year, I keyed it out to Erizona sp. female (eyes do not meet at the top of the head) but I am not quite sure about it.

So here is how I keyed it out:
1. black abdomen with partial or complete transverse yellow bands,
2. assumed bare postpronotum (otherwise the key would lead me to Blera sp. which has pilose postpronotum),
3. abdomen tergites with no black velvet bands,
4. face mostly yellow,
5. eye with rounded emargination on posterior margin (as oppose to triangular emargination),
6. R4+5 vein conspicuously curved,
7. Vein R4+5 distinctly curving into cell r4+5,
8. Face yellow with black medial spot or stripe; R 4+5 shallowly curved into cell r4+5,
9. Third and fourth abdominal tergites with yellow margin = Eriozona (Megasyrphus).

I could not stand not knowing how wrong I was regarding the identification of the species, and so I enlisted the help of BugGuide.  Trusting the experts over there, they identified it as a Transverse Flower Fly (Eristalis transversa), which based on other photos does look similar to my photos.  Going back to the key, I keyed it backwards knowing the species (or subgenus Eoseristalis).

- Hairy bulky flies with long, black/brown/yellow hairs, similar to bumblebees and honeybees
- Face either concave, or somewhat swollen, or with central tubercle
- Arista bare, or with inconspicuous hair (at most slightly longer than arista width)
- Vein R4+5 sinuous
- Cell r1 closed before wing margin; hind femur neither enlarged nor with prominent lobes or extensions

- Katepimeron, half of anepimeron, meron, and metapisternum bare = Eristalis (Eoseristalis)

You can see the conspicuously curved R4+5 wing vein and closed r1 cell.



Face is yellow with black medial stripe (not seen here).


The yellow bands extending all the way to the margin.

Eye with rounded emargination on posterior margin, and face concave.

After taking some photos, I put it back outside on a dandelion flower where she can warm up and fly away.  Thank you, fly.

Here is more information on Eristalis spp. - link.