[For full-size image, click this link...then click the image again after it loads in your browser window.]

I spotted this Ammophila as it was dragging its paralysed prey along the ground. Habitat was creosote scrub/open Joshua tree woodland.

Can anybody ID the caterpillar? If so, please respond within the comment thread for the post below:

 

For the Ammophila my initial best attempt at species ID was A. aberti...but eventually I concluded it's either: 1) something described after Melander's 1903 paper (in literature I wasn't able to access); or 2) something still undescribed. Details below...

WARNING: Reader discretion advised below! What follows is a long and detailed log of my attempts to ID this wasp. It grew over time, as I revisited the process, found additional references, and realized and corrected various errors I'd made. At this point it's meant to remind myself of how I proceeded; and to provide links to various references that may be of use later. It's also a page I can revisit when I need reminding that it's sometimes better to just post images and hope an expert can help with ID's, rather than try to stubbornly plow through the process yourself :-) Though, sisyphean as it may have been, I probably did learn more than I would have if somebody had just given me an ID.

I found citations to a number of Ammophila references by Menke (see info page), but just one was available online in its entirety, and it didn't have a key. The best key I could find online was quite old:

  Melander, A. L.(1903), Synopsis of the North American Species of Ammophila. Psyche 10:156-164 (Read online here).

Choices here for the first two couplets in Melander's key (on pg 158) are clear:

  1) Front wings with three submarginal cells.......2
  2) Petiole consisting of entire 1st segment and at least portion of the 2nd (Ammophila).....18

At couplet 18 the choices are:

  18a) Pro- or meta-notum transversely stigose....19

     vs.

  18b) Disk of thorax punctured or smooth, never with complete transverse strigae...34

The term strigose here means "marked with fine, close-set grooves, ridges, or streaks", and strigae are such grooves, ridges or streaks. Examining my images (especially in the 3rd one in the series) I think I do see fine transverse grooves on the metathorax of this wasp. So proceeding to couplet 19 would seem a reasonable way to go. However, I noticed that if I also follow the lead to couplet 34, then subsequent couplets refer to "striae" (which is a different word than strigae, but would seem to have nearly the same to meaning to me)...so I went both ways.

First I followed couplet 18a), leading to:

  19) Thorax or legs in part red.....20
  20a) Head red; metanotum transversly striate......A. ferruginosa
  20b) Head black; metanotal straie becoming rugose laterally.....A. collaris

The head is clearly black not red, so I went with A. collaris...but that species is now in synonymy with A. ferruginosa, so the choice appears moot.

But this route appears to be a dead end, as Cresson's original 1885 descriptions of both these species (see here) state they have a ferruginous (reddish) thorax; and (along with A. pruinosa, to be mentioned below) they also have first antennal joint red; and red on the mandibles...none of which fit the wasp here.

So going with couplet 34) leads to:

  34a) Legs at least in large part red.....35
  35a) Head and clypeus black; metanotum at least centrally with transverse striae....36

     vs.

  35b) Metanotum sharply, densely, and obliquely striated ; face and clypeus silvery.....aberti

The choice between 35a) and 35b) here is problematic. On the one hand my specimen has a silvery face and clypeus which goes to aberti. On the other hand, the straie appear transverse (not oblique) which suggests 35a), but the clypeus isn't black!

Going with 35a), at couplet 36) one would need either:

  36a) Central part of metanotum pubescent (leading to A. pruinosa, which was eliminated earlier); or

  36b) Pleura with three large silvery pruinose spots....A. femur-rubrum

But neither of those characters seems to fit well here. For reference, the current spelling of the latter is A. femurrubra(1), and its original 1894 description by Fox can be read here.

So it seems the better choice is to go with 35b), leading to A. aberti.

The original 1852 description of A. aberti by Haldeman can be read online here, and Eric Eaton has a post of A. aberti determined by A. S. Menke below:

 

The specimen in my post agrees fairly well with that in Eric's post and with Haldeman's description, vis-a-vis head, legs, thorax, and black spot at apex of abdomen. But there are two discrepancies I see:

  1) Haldeman describes the peduncle (= first thin segment of the abdomen) as black, which agrees with Eric's post but not mine; and
  2) While Haldeman's only specimen was missing its head, Eric's image shows the mandibles being mostly red, while my specimen here has mandibles entirely black.

If those characters can vary in A. aberti, then perhaps that's what I have here?

However, many(!) new species have been described by A. Menke (and others?) since 1903, so I'm hoping someone with expertise might be able to help place this series to species.

Postscript: I just found this reference for A. aberti, which indicates the middle of the mandibles are ferruginous. So seems like nothing in Melander's 1903 key fits my gal here.