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Syrphidae? Eumerus? - Hiatomyia

Syrphidae? Eumerus? - Hiatomyia
Estero Trail, Point Reyes National Seashore, Marin County, California, USA
May 11, 2013
Size: 1 cm

Images of this individual: tag all
Syrphidae? Eumerus? - Hiatomyia Syrphidae? Eumerus? - Hiatomyia

See the barely visible plumose arista.

Moved from Hiatomyia.

Moved from Cheilosia.

Moved from Flies.

Could be Eumerus, but I'd guess Xylotini
Tough to ID. See:

Thanks Ron -
that would make more sense, I think - my overall impression was of a fairly large robust fly - I thought at first it was a tachinid or something similar.

Cow Parsnip
Ken, This is on common Cowparsnip, Heracleum maximum, isn't it?

No idea, Scott -
I don't know my flowers very well unfortunately - if you say so! :)

Flower head size
Do you recall of it was a large flower head, huge leaves with a thick diameter stock?
It looks like Cowparsnip to me, it has a fused ovary, and the only other one in my area I can think of would be the more delicate foliage of the Poison Hemlock.

I'm just wondering do we have a single plant preference for this fly.

Actually it should be Cowparsnip, the dark stamens, it's the only one of those confusing bunches of flowers with dark stamens, though, I don't know Point Reyes..


Thanks for the info!
It's been way too long - 1.5 years, and I don't remember anything about the plant, sorry. I do think the plant associations can be very important, but I just don't remember anything about this one...


If you would, for not reason more then to assuage my curiosity, would you lean this flower and try to photograph those who are dependent on it?

Oh my that's a link.

We've only got 3 images, but they are all in Cowparsnip, and all between April 30th and May 11th. It might give us an advantage in finding more.

Heracleum is an ideal pollen
Heracleum is an ideal pollen and nectar source for Syrphids, it is the perfect landing platform and easy to reach with even a short proboscis. But there are some European Cheilosia which use Heracleum as larval food plant, so there might be a closer association, although we need to be cautious because many Syrphids will use this plant just as an adult food source.

Thanks Martin -
you agree with the switch in the genus determination, then?

I am not 100% sure if Hiatomy
I am not 100% sure if Hiatomyia is a valid genus, but if, the plumose arista is the character, and this would make this fly a Hiatomyia....

I am in agreement with Dr. Ha
I am in agreement with Dr. Hauser in his skepticism. However I made my diagnosis based on the currently accepted taxonomy. There are number of genera which switch internally between plumose and pubescent arista. However this should be resolved with the upcoming World Syrphidae phylogeny which will likely produce some drastic changes in generic and higher level concepts.

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