Long legged green flies (Condylostylus)

I'm sure everyone has at least SEEN the very common long legged green flies, and probably you've photographed them, too. It has bugged me (pun intended) that so many sit at Genus, so I finally got around to digging into why. Some seem so obvious with particular wing patterns. Long story short, you can use the wing pattern to narrow it down to a group, but to get to species you need clear pics of the bristles on the legs and possibly the coxae (the segment connecting the leg to the abdomen.) So, I'm going to take a second to go through my observations and move them all back to Genus, unless I can get a good zoom on the legs. If I've ID'ed your obsv, tag me and I'll update it, too!

Here are some links to help you ID if you decide to tackle it!

Here's the basic key from BugGuide:

Different species are commonly found together, even on adjacent leaves.

Key to species groups found north of Florida and Texas, possibly unreliable for females along the Gulf Coast.
Notes: In some species wing markings are optional. When markings are present they may be faint and not continuous, reduced to darkened areas along veins. The standard U shaped wing pattern is two bands across the wing joined by a band between C and R5. A few species without wing markings may have a faint cloud near the tip of R2+3.

C1. Legs and antennae of both sexes completely black. → C2
C1'. At least part of fore or mid legs beyond coxae yellow or brown. → C4

C2. Male: usually pure blue, costal cell expanded, costa with long cilia, R1 ending distinctly past midwing, second segment of fore tarsi very short. Wing unmarked. Southeast USA, Neotropics. → C. mundus
C2'. R1 not ending past midwing, usually shorter. Wing usually with U-shaped mark. Never completely blue; sometimes with blue reflections. → C3

C3. Face with long, pale hairs. Segments 2-4 of fore tarsi similar (female) or 2-3 similar and 4 longer (male). East of Great Plains → C. patibulatus
C3'. Face bare or with dark hairs. Great Plains to Pacific → C. melampus, C. coloradensis, C. pilicornis.

C4. Antennae longer than head and thorax combined. Fore and mid tibiae with about four very long hairs. Femora of both sexes dark. → C. comatus group (comatus, crinitus, villosus)
C4'. Antennae of normal length. Femora of female usually pale. → C5

C5. Wing with U shaped marking, sometimes very faint or only present along veins → C6
C5'. Wing unmarked, occasionally with cloud near tip of R2+3 → C7

C6. Femora and tibiae of both sexes yellow. East → C. sipho group (six species)
C6'. Femora of male dark. Georgia to Arizona → C. inornatus, C. leonardi, C. quadricolor (unrelated species)

C7. Fore and mid femora of both sexes yellow. Face bare → various rare species
C7'. All femora of male dark, of female yellow or dark. Face bare or with long, white hairs → C8

C8. Tibiae yellow, hind tibia usually darkened near tip. M1 gradually curved, making approximately right angle with base of M. Face usually with pale hair. Male mid basitarsus usually with conspicuous curved bristles. Mid tibia of female with strong bristle near one third length. → C. caudatus group (s.l.)
C8'. Mid basitarsus of male with row of fine hairs. Legs black except fore tibiae of male and fore and mid tibiae of female. Hind tibia of both sexes and mid tibia of male with row of about 12 bristles. Face bare. → C. longicornis

Since we see a LOT in the C. sipho group, the key for those species is here:

Six species:
    --sipho has a row of bristles on the mid tibia and not on the mid basitarsus --scaber has a row of bristles on both tibia and basitarsus, and yellow fore coxae --viridicoxa has a row of bristles on both tibia and basitarsus, and non-yellow fore coxae --brimleyi has a plain mid tibia and mid basitarsus "with a series of short, rather blunt, erect bristles toward base and many minute, erect, scale-like hairs on anterior surface" --furcatus and longitalus do not have long rows of uniformly spaced bristles

And also a diagram and description of the parts of fly legs:

Publicado el julio 3, 2017 12:35 MAÑANA por kimberlietx kimberlietx


One quick note on C. mundus (which is the bright blue one.) Females are green, so they aren't as easily ID'able.

Publicado por kimberlietx hace alrededor de 7 años

Aaaand just for an idea of difficulty... @annikaml posted a GREAT pic and I still can't figure it out. Take a look at here at the kind of pic you would need to get a species ID: http://www.inaturalist.org/observations/1601141

Publicado por kimberlietx hace alrededor de 7 años

My photo is pretty poor. Can this even be IDed to genus? http://www.inaturalist.org/observations/3340998

Publicado por vermfly hace alrededor de 7 años

My little fly with green eyes an entomologist from PA says is genus Neurigona. So glad you and she are out there paying attention. Anyway, suddenly seeing that "gall midge" with a big hunk o' prey in its mouthparts was an eye-opener. But I guess a lot of the long-leggers are insectivores, aren't they?

Thanks again,

Publicado por mokennon hace alrededor de 7 años

@vermfly I don't think so. :(

Publicado por kimberlietx hace alrededor de 7 años

@mokennon I saw your gall midge and looked through my observations because it seemed familiar, but I didn't find it. I had another fly with long legs from a different family, but darned if I can find it now.

Publicado por kimberlietx hace alrededor de 7 años

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