Jacques Hausser sent pictures of hoverflies (syrphids) as well as his identifications. Hoverflies, in the family Syrphidae, are true flies—that is, they’re members of the insect order Diptera. Syrphids feed on nectar and pollen, and are thus sometimes called “flower flies.” Many of these harmless flies, like the four below, are Batesian mimics of more dangerous insects: bees or wasps in the order Hymenoptera (those having four wings rather than the flies’ two), probably because both frequent the same areas. The hoverflies are clearly evolved to deceive predators. Jacques’ captions and notes are indented.
Volucella zonaria – obviously trying to mimic a hornet [JAC: I’m not sure what those red sacs are attached to the thorax; you can also see them in the fourth photo.]
Helophilus pendulus:
Xanthogramma pedissequum:
Chrysotoxum bicinctus:
And reader Christi sent this photo of a rattlesnake (species unknown, but not for long, I suspect), lying cryptically in the leaves. Watch where you step!
Closeup:
The red on the Chrysotoxum bicinctus is a mite sucking away… I think. I have photographed them on opiliones…
The mite might not be sucking away particularly, they often use insects as a transportation mechanism, rather than as a host to feed on (the technical term is phoresis.)
Oh yes – the term is one I have come across but would never have remembered. To get to a bird maybe? (Or a cheap holiday!) They definitely suck at the joints of opiliones
eg
http://dllavaneras.deviantart.com/art/Mite-infested-harvestman-164298954
Lovely pictures by the way. And Jacques does not say where they were taken…? North America?
It may be. I recognize all but the 1st one as species in my region.
Yet the Xanthogramma pedissequum is a European species & comparatively rare… introduced?
By the way, in case some of you missed this article last April, you don’t have to be a good mimic to get an advantage…
http://www.cell.com/current-biology/abstract/S0960-9822(14)00262-0
A potential prey only has to look less appetizing than her neighbor to avoid being eaten. A prey species should not be expected to evolve mimicry that is any more “perfect” than is needed to fool predators “enough” to live to make babies. I would expect to learn that the more “perfect” the mimicry, the greater the selection pressures and the longer the relationship with the affected predators.
Makes perfect sense to me! I can’t access the whole article but by the abstract it sounds interesting!
Also interesting to me is the idea that the really impressive mimicry we see had to start somewhow, and it sounds like this paper offers some insight how that party gets started.
Unfortunately this insight is wasted on the “what good is half a wing?” crowd.
It’s also worth remembering that our eyes and brains are not the ones the mimic is trying to fool. So our assessment of “perfect” mimicry isn’t directly relevant to the mimic’s success.
No, they are european; the first was taken on Sark, Channel Islands, but it is quite common everywhere, and the last one (Chrysotoxum bicinctus, with the red parasitic mite) in the swiss Alps. The two others were shot in my garden, on the lower slope of the Jura mountains, above the lake of Geneva (46°27’52.08″N, 6°14’7.26″E if you want to see the place) – I planned to send more comments to Jerry, but I forgot…
Very nice anyway!
Beautiful fly photos!
I’m quite fond of syrphids. I see many more of them than hornets, for that matter.
The snake is a timber rattlesnake, Crotalus horridus…
I concur with this ID, having helped capture one with friends years ago.
Looks like a canebrake rattler – same species, but a characteristic colour pattern, and it occupies the more southeasterly part of the timber rattler’s range.
However, almost all of my rattler experience is with Prairie rattlers so I could be wrong here.
The “canebrake rattlesnake” was described as a subspecies of the timber rattler, and was called Crotalus horridus atricaudatus. C. h. atricaudatus is no longer formally recognized and all populations of C. horridus are listed as such.
Too bad! It seems to me that C. h. atricaudatus is a recognizable taxon…!
Are canebrake-phase individuals geographically circumscribed? If not, that’s likely the reason the taxon was invalidated.
The problem is as much philosophical as taxonomic. The subspecies concept has been used and abused for well over half a century and some (most) herpetologists have gotten tired of the literature getting cluttered up with trinomials that don’t reflect the true situation. It would be really useful for someone to undertake a phylogeographic study of lots of tissue samples of the species from throughout its range and really determine whether the entire cluster is one species or several unrecognized species hiding behind the nominate form. I would be glad to collect some tissue samples from South Carolina and Georgia to donate to the cause!
I’d be willing to help out with that. The specimen we caught was in southern South Carolina.
I note that the former subspecies of the milk snake, the scarlet kingsnake, has been elevated to full species status: formerly Lampropeltis triangulum elapsoides, now known as Lampropeltis elapsoides. This seems appropriate.
Looks like the job has already been done, and the primary divergence in mtDNA turned out to be east and west of the Appalachians rather than north vs. south as implied by the subspecies concept.
Of course nuclear genes may show a different pattern (or patterns), but that’s exactly why subspecies is often a useless category: gaps or clusters exist with reference to a particular measure of similarity or difference, and different measures imply different histories which (in sexually reproducing species) can all be true.
Gorgeous photos. Thanks!
Macrophotography of syrphids must be especially challenging. Excellent job.
Challenging, and something I couldn’t do. My top three irrational fears in no particular order are; small black & yellow things that fly, jelly fish and dropping my keys in a sewer.
My fears are similar with the addition of cellulite.
😀
Paul, my Dad once dropped his keys through the planks of a dock, into the Pacific Ocean.
Parts of the Pacific Ocean are quite shallow near the edge, but I guess it maybe wasn’t one of those bits.
Nah, he was a captain in the Merchant Marine, and the ship (maybe a C3?) was docked there…
But she could not have chosen otherwise … !
That snake would probably kill me dead. The only advantage I would have is that running trails super fast would allow a step on her back before she could acknowledge to strike.
You mite not have known but those little red thingies are backpacks.
They’re courier hoverflies.
Hover flies are very neat, especially the really tiny, highly maneuverable ones. These seem too look like what I classify as “biting flies”.
Christi, great set of snake photos! That rattler would be so hard to see on a hike through the country…Good thing they (usually) have early warning systems.