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Photographed two days ago in Tilburg (The Netherlands

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Crabronidae. Looks like a Cerceris sp. Do you have another photo where to check better femora 3? So I can confirm the genera

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too bad its the only pic that i got, it was gone after two clicks....

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Anyways, we know the family! :)

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I think, Ectemnius.

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Can be, but without checking wing we cannot be certain about its subfamily

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Is the head shape not sufficiently distinctive?

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Never heard/read about this character. Where have you found it? About head, antennae are in a frequent posture of Ectemnius, but I don't see other things.

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I also think it is an Ectemnius male (antannae looks characteristic enough.) I would even risk suggesting Ectemnius continuus as a tentative ID.
(Wing venation would not really help, it is the same in a number of genera within Crabronini.)
Greetings,
Henrik

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I didn't know you had Ectemnius continuus. I have seen it a few times in USA. This does look similar. Among North American species, according to an expert in the group, it is distinguished from most by the all-black third tergite and from all by a "small inner process on the second tarsomere of the male mid tarsus".

On BugGuide subfamily Crabroninae is named "square-headed wasps". http://bugguide.n...520/bgpage

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Indeed Cerceris is not from tribe Crabronini, and not even from subfamily Crabroninae.


And how can you say is a continuus and not a rubicola from this photo?

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In the region where I live (S. Hungary), E continuus is by far the most frequent Ectemnius sp. Here, most, but not all, specimens have black third tergite. In the case of males, the shape of the lower surface of the antennae, when clearly seen, is sufficient to distinguish it from other Central European/Hungarian species. That's the reason I think it could be that sp.

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Of course, it is a tentative ID, and not 100%!

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I see piros. But rubicola is really similar to that species. You need to check propodeum, clypeus, and the full antennae, in females, while is important to evaluate tarsomeres in males

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That's why it is a "tentative" ID ;)

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Sure, most of IDs, by non macro/micro detailed photos are.
But better to use known characters, otherwise the ID wont'be realiable:)

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Well, the second flagellomere in the photo is discernible, and clearly longer than that of (male) E. rubicola. I consider this a reliable character. Don't you?

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I'm sorry, but the answer is: No. Length isn't a useful character in this specific case. To distinguish these two species the 3rd antennomere is a useful character, but it's not used its length, while a ratio of its dimensions :)

Juergen, I'm quite sure, was right saying Ectemnius ...even if we cannot stress its characters.

BTW: Yesterday I verified, and rubicola can be excluded (because of the ratio of its 3rd antenna's ratio L/W). Problem is that its ratio exceeds that of a continuus (>2!!).

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OK, I am not a paid advocate of Ectemnius continuus Ltd... Ectemnius sp. is fine with me :) Just thought it worth considering E. continuus, since color pattern agrees, shape and proportion of antennal segments (BTW, I don't think you can reliably mesure L/W ratio in the photo) agrees (in my view!) with that sp. That's all.

Best regards,
Henrik