https://bugguide.net/node/view/2037370

I just posted a specimen from 2011. Both male and female.

Delta higletti rendalli (Bingham, 1902) (Delta esuriens does not occur in the US).

Bingham. (1902.) Ann. Mag. Nat. Hist., (7), X, 1902, DALLA TORRE, Gen. ins. Vesp., 1904, p. 24.
Bequaert. (1918.) [Revision Vespidae of the Belgian Congo]
Bequaert. (1926.) [A key to the African species of Eumenes s. l.]
Menke & Stange. (1986.) Delta campaniforme rendalli and Zeta argillaceum established in southern Florida [...]. Florida Entomologist, 697-702.
Carpenter et al. (2010.) [Eumeninae of the Ethiopian Region]

Marco Selis is a vespid expert and is familiar with both species. He has verified that these are D. esuriens and not D. rendalli. Note that the metanotum is yellow here, which shouldn't occur in rendalli. This is not the case in the specimen that was brought up on iNaturalist photographed by abitsis, where the fully red metanotum corresponds to rendalli. Even when rendalli has an extensively yellow pronotum (more-so than those photo), the postscutellum should be red rather than yellow as far as I'm aware.

For the iNat. photos det. as esuriens, J. Carpenter confirmed they are D. higletti rendalli (which the D. rendalli taxon page also should change to). He didn't have a conclusion on these current photos, although I'll try to ask A. Menke's opinion and update here. My basis so far:

There's color variation in D. higletti rendalli specimens Menke det.:
https://api.gbif.org/v1/image/unsafe/http%3A%2F%2Fn2t.net%2Fark%3A%2F65665%2Fm3df13bc36-e596-4d68-80de-e9298f2a1758. The middle-right specimen possibly has a yellow metanotum. https://api.gbif.org/v1/image/unsafe/http%3A%2F%2Fn2t.net%2Fark%3A%2F65665%2Fm36a683f69-c52d-476c-9988-6100c0d7cdc1. The specimens have a yellow metanotum.

Menke & Strange (1986) noted only higletti rendalli (current name) is introduced to FL (D. esuriens not known to the New World). There's also significant color variation in many Delta (esp. considering ssp.), which they noted for higletti rendalli: "In most FL males pronotal dorsum is reddish brown except black posterolaterally and traces of yellow along transverse carina. In one male reddish brown is replaced by yellow. The Zaire males studied display both patterns." I think D. esuriens pronotum (viewed from above) is more entirely yellow in all ssp. (esuriens, okinawae, gracile). Compared to D. higletti iNat. photos, the records here, and Menke's specimens, which are red or have a reddish end or gradient.

I'd be very hesitant to say that Marco Selis, a specialist in this group, is wrong if you haven't actually studied the genus. In any case, I've also passed the images on to James M. Carpenter for a second opinion. He notes "this one is definitely not higletti rendalli." So we can definitely say that it's a more recent introduction, which does happen, even if rarely (case in point: Vespa mandarinia in Washington and British Columbia).

My current opinion is D. esuriens is one possibility, although further assessment is needed to fully demonstrate it's not another spp. I've spoken to J. Carpenter and A. Menke, who didn't conclude without examining specimens. I'm also basing my ID comments on the following:

I recently corrected iNat D. esuriens FL records = D. higletti rendalli; D. rendalli = the latter; and that it can occur more yellow (vs. mostly red).

Re: esuriens distinguished by yellow metanotum. Some D. campaniforme have yellow metanotum, and some D. esuriens lack one. They have significant color variation (1, 2, 3, 4) as does D. higletti (1, 2) (specimen photos on GBIF), the full extent of which isn't described in lit. yet. It seems possible D. higletti or other spp. could have a yellow metanotum. Lastly, the pronotum seemed to (possibly) have more red/black in the corners than the more typically entirely yellow of esuriens (uncertain of that).

Delta ID difficulty/cryptic spp. recently came up in an iNat discussion about esuriens vs. campaniforme ID, which I also asked J. Carpenter about. According to my lit. review, there are some contradictions or missing info. in lit. including ID keys, making it currently impossible to determine which spp. it is in some cases. And by contrast, D. higletti seems even less well-studied. Having said that, esuriens is a possibility. If it were, I'd wonder which subspecies. I'm also interested to hear any additional expert opinions on the iNat. esuriens/campaniforme ID matter.

My conclusion for now is D. esuriens is possible, possibly likely. There does remain some unknown information re: the unknown extent and variety of species color variation and minor contradictions in existing Delta keys, which technically would be best to clarify further before a definite ID. That said, I am fine with this ID for now in that it's most likely given current information.

I just saw this thread, I am going to post some images from 2011 in South Florida of a similar delta sp.

good idea.

thanks for all your careful research on this (as well as many other wasps, lacewings, etc) in recent months! much appreciated

...in some instances esuriens and campaniforme lack constant color differences (re: the ones you list) and so can't be distinguished without examining minute antennal structures. Whether or not that is accurate was unable to resolved using past and present ID keys, since they have minor contradictions with each other. e.g. a recent Vietnam key reports they do have constant color differences. I agree the current photo isn't pyriforme (yellow on thorax is very different shape) or unuicingulatum.

By the way just to share with everyone, a new Delta introduction was recorded in California today. That one does look more unambiguously like esuriens (introduced perhaps via Pacific direction, e.g. Hawaii?).