Hi Andy, Fancy running into you here. I was thinking the flower is an eriogonum, perhaps nudum. They were growing in a relatively small area with many insects nectaring. It is a perfect situation for photography, limited resources in a small area. The insects tended to stay put while I was approaching and photographing. (I was going to attach another photo that showed the leaves but can't figure out how to do it). Stuart

I think the flower is a Wild Chives.

Eulonchus, probably sappharinus, but the key characters that separate E. sappharinus and E. smaragdinus are based on the length and shape of the proboscis, which can't be seen in this photo. Still based on locality and the male and female color they are probably Eulonchus sappharinus.

Dennis, Thanks for your help on the ID. We have the authority for Acrocerids just over the mountain, Evert Schlinger, but I can't raise him by phone or email. This is a great forum, thanks to everyone who helps out here!

Stuart

Stuart- I talked to Ev and he thinks it is likely E. smaragdinus, and a good record for that. But Dennis is correct above and without the proboscis they can't really be determined with much accuracy.

Beautiful picture! Did you collect these specimens?

Hi Chris, Thanks for checking with Ev. No, we didn't collect, we were in the NP so that would be an issue. I am putting together some photos to send to Steve Zachary, one of the park rangers, so he will appreciate having the correct name. I rarely collect now, the camera equipment is usually a full load and of course how do you satisfy both urges at once: snap or snag?

Just to add to the discussion, the proboscis on E. smaragdinus is longer than the body and sticks out from underneath when the fly is at rest. The female probing the flower doesn't look like she could have a proboscis that long, and the angle is just off for seeing the condition of the male. They are beautiful flies! I usually think of E. smaragdinus as the prettier of the two species, and these specimens certainly are stunning.