Small Green Caterpillars - Sphacophilus cellularis

Moved tentatively pending further input from Dr Smith

… v belov, 9 November, 2009 - 6:45pm

Argidae

I leave this as a family id for now. Could the plant be Ipomoea or Convolvulus? There are only a limited number of argids in Virginia, and by the process of elimination, it seems to be Sphacophilus cellularis which feeds on these plants. I'll check specimens and post another comment if I find it is.

… Dave Smith, 9 November, 2009 - 6:43pm

Japanese knotweed

I'm pretty confident the plant in the linked image is Japanese knotweed (Fallopia japonica, syn. Polygonum cuspidatum). Do any species feed on Polygonaceae? And might there be a species introduced from Japan with this host plant? Of course, the other question would be, Ashley, are you certain that was the plant they were feeding on? I would believe that the plant in the above image is something in the morning glory family about as readily as I'd believe it's Japanese knotweed.

… Charley Eiseman, 9 November, 2009 - 8:52pm

Yes

that was definitely the plant they were feeding on, and after consulting photos of Japanese knotweed, it seems that's what this was, down to all the distinctive bits like the pink coloring and structure.

Thanks!

… Ashley Bradford, 10 November, 2009 - 10:11am

host plant

Thank you for the confirmation of this plant. It presents an interesting little problem. There are sawflies on Polygonaceae (Polygonum, Rumex, Rheum), but they are tenthredinids and these larvae are not those. I am not aware of any sawfly species introduced with the knotweed. Maybe the species I think it is has a broader host range than expected. Adults would be nice. I am not too far from Mason Neck Park in Fairfax Co. If the larvae were active the first of July, adults may be flying around by mid-June. Or if you find larvae next year, maybe I could come over and get some for rearing. The problem is that one needs a permit to collect in state parks.

… Dave Smith, 11 November, 2009 - 8:24am

That IS interesting

I'll be keeping an eye out for these in the future now. How well do you know the park? These were on a knotweed at the edge of the little pond where the kayaks put in - between the pond and the boardwalk there. I'll definitely be in touch if I find more. I didn't know a permit was required to take an insect from a state park! Glad I know now.

… Ashley Bradford, 11 November, 2009 - 11:35am

sawfly vs caterpillar id tips

In addition to the proleg differences, sawfly larvae have only one eye on each side of the head; lepidoptera larvae have 6. They're low on the front of the head, just slightly offset to the sides, right above the mandibles. Very tiny, of course, and only visible with magnification or on a large, pale-headed larva. They're easiest to see on a recently-molted larva, before the head colors up.

With their black heads, seeing the eyes on these little guys is certainly very difficult; I do see a slightly different area of light/texture where the eyes are but at this magnification can't count them. If you have any photos at higher magnification, or can zoom in/enlarge this image, it might be possible to count the eyes. (Really all you need to know is one, or more than one - don't have to count all 6 to know it's a caterpillar.)

… Abigail Parker, 6 July, 2009 - 9:45am

That's good to know, too

Unfortunately the large version of this photo is blurry (I was able to sharpen it a bit at this smaller size), but I'll check it to see if I can tell.

… Ashley Bradford, 6 July, 2009 - 10:23am

These are certainly sawfly larvae

And I think you were right in your original impression of the larva in the linked photo. You can see the prolegs going right up to the true legs in these larvae; I think we would see the same in your other shot if it had been taken from a slightly different angle. I can't say for sure whether they're the same species, but it seems probable. Knowing the plant species would help in figuring out the ID.

… Charley Eiseman, 6 July, 2009 - 8:58am

I took a picture of the plant,

but I'll have to post it to some plant equivalent of BugGuide to find out what it is. I think there is one - have to remember what it is. =)Thanks for the notes on larvae.

… Ashley Bradford, 6 July, 2009 - 10:22am

Plant

By all means, post the image here, and we can just frass it once it has been identified. That's common practice on BugGuide. (And let me know if you find the plant equivalent of BugGuide--I've never heard of it, and I'd love to see it!)

… Charley Eiseman, 6 July, 2009 - 10:39am

If I get stuck with a plant...

I post on this forum as they have an ID section: http://www.botanicalgarden.ubc.ca/forums/

Other botanical gardens may have forums as well, this one is just in my area. They have helped with plants from all over.

E-flora and Calflora are also useful sites that don't always offer ID, but they do have a lot of photos for comparison if you have an idea of what you are looking at. Of course that only covers the west coast.

… Botany, 24 July, 2012 - 9:53am

That is useful -

thanks so much!

… Ashley Bradford, 24 July, 2012 - 10:56am

....

Charley,
I have started a collection on my website. Currently I only have 237 images but they are fairly common plants and trees. Obviously it's not BugGuide-like but it's a start.

Please see homepage here and plants page here.

… Sam Houston, 6 July, 2009 - 11:01am

Great, thanks! Done! =)

I thought Dave's Garden might do it, and I did find a section on there, here.

Another on gardens.com

And on gardenweb

But none of them have the nice gallery of photos you can just look at all at once like BugGuide to see if anything jumps out at you as something you know right off, which I love about this site.

Oh, this also looks like it could be interesting.

… Ashley Bradford, 6 July, 2009 - 10:51am

That looks like

Japanese knotweed, unless there's a native lookalike in Virginia. I think Japanese beetles are the only insects I've ever seen eating it, so I wonder if these are introduced sawflies or maybe a species that feeds on related members of the buckwheat family and has broadened its diet.

… Charley Eiseman, 6 July, 2009 - 10:57am

Oh hooray!

Another invasive species. :-P

That does look like it - it even flowers like that, with standing strands of tiny white flowers. Thank you!

… Ashley Bradford, 6 July, 2009 - 11:15am

They were

on a leaf adjacent to this one - are they a different instar of the same thing?

… Ashley Bradford, 6 July, 2009 - 1:32am