Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Flies (Diptera) » "Aschiza" » Hover Flies (Syrphidae) » Syrphinae » Bacchini » Platycheirus
Photo#1054833
Flies clinging to flower stems - Platycheirus
Copyright © 2015 Debbi Brusco

Flies clinging to flower stems - Platycheirus
Windy Hill OSP, San Mateo County, California, USA
April 3, 2015
Size: ~15mm
On quite a lot of the Ranunculus californicus these flies clung motionless to the stems just below the flowers. Some had distended abdomens like this one, and some looked dessicated. It was about an hour before sunset, and cold. We weren't sure if they were gravid or had some kind of parasite.
There were flies also on the next night.

Images of this individual: tag all
Flies clinging to flower stems - Platycheirus Flies clinging to flower stems - Platycheirus
Contributed by Debbi Brusco on 11 April, 2015 - 3:15am
Last updated 23 October, 2015 - 9:12am

Moved
Moved from ID Request.
… Debbi Brusco, 11 April, 2015 - 1:39pm

Looks like Platycheirus sp.,
Looks like Platycheirus sp., but it'll be harder to get further than that because of the fungus...
… Kelsey J.R.P. Byers, 11 April, 2015 - 1:12pm

 
I wasn't able to see the spur
I wasn't able to see the spurious vein on the first photo, but now that you said that, I can see it in the second.
Hadn't thought of a fungus...
… Debbi Brusco, 11 April, 2015 - 1:30pm

Fungal infection
I have seen the same once: many syrphids on flower stems, dead. I can only imagine that they indeed rest there at night and are overcome by the fungus when they are clammy and cold. Of course, some fungi seem to have the ability to make the host climb to exposed spots before death so the spore have a better chance o disperse. I think you see differences in the corpses because only in one case the fungus is mature
… margarethe brummermann, 11 April, 2015 - 11:02am

Disclaimer: Dedicated naturalists volunteer their time and resources here to provide this service. We strive to provide accurate information, but we are mostly just amateurs attempting to make sense of a diverse natural world. If you need expert professional advice, contact your local extension office.

Contributors own the copyright to and are solely responsible for contributed content.
Click the contributor's name for licensing and usage information.
Everything else copyright © 2003-2024 Iowa State University, unless otherwise noted.

Bugguide is hosted by:

Plant Pathology, Entomology and Microbiology at Iowa State University logo