Ichneumon wasp behaviour??

[crazylilthing]

This is my first post, so hello.

I've been watching a largish black wasp that shares some of the characteristics of ichneumons that I've seen in the past.

This one keeps flying back to a low brick wall, finding a marker of some kind, and then, with some effort, locating a horizontal entrance between two courses of brick, where some mortar is missing.

A characteristic trait is its constantly animated fast crawling and twitching, very long antennae.

Can anyone give me a genus or a short-list based on this behaviour and nesting habitat (presumably?) alone?

I have seen a similar one prowling about on very gravelly soil with low organic content (nearly pure mineral) at the edge of a very dry rockery.

I'm sorry but I don't have a camera that's up to taking a shot of this.

Thank you.

[Geoff F]

Can you help to narrow down the choices here. Is it a wasp or bee? Eg. does it have a clear very narrow waist like a wasp or a less obvious more bee like waist. They can be tricky to seperate.

I am thinking, Digger Wasp or Mining Bee. Have a look for these in the WAB Gallery and see if anything looks similar. Possibly one of the Andrena species of bee. The behaviour is similar to the Spider Hunting Wasps except for the masonary thing (as far as I am aware).

With regard to size, would you say 10mm head to tail or larger? And how long are the antennae compared to body size? If they are as long, or longer, than body length and there isn't a clear waist it could be one of the Bug species (Hemiptera family).

[crazylilthing]

Originally Posted by Geoff F

Is it a wasp or bee? Eg. does it have a clear very narrow waist like a wasp or a less obvious more bee like waist. They can be tricky to seperate.

Definitely wasp-like in appearance. It has irridescent wings, a narrow body, wasp waist.

Remarkable is this characteristic all-over twitching behaviour - wings and antennae.

Originally Posted by Geoff F

With regard to size, would you say 10mm head to tail or larger?

I'd say over 10 mm.

Bears some similariy to Stilbops?? (But don't want to introduce a red-herring.)

Not at all bee-like. Very very long, wasp-like antennae.

The one I originally saw on the rockery four days ago was there again this afternoon. It was kind of hunting around in a systematic way over the gravelly soil.

[crazylilthing]

Pls excuse reply to reply to my own post, but I've been looking at the Gallery and it bears some resemblance to Trypoxylon sp.

Note I'm not saying that it is -just that it looks a bit like that.
I am beginner to all this, but I am already mesmerised to see that you can get wasps from a different genus with superficially similar appearance! I'll be buying a book on hymenoptera id soon!

Reminder on habitat. Remember, the two I've seen were
1) crawling into a hole leading to a horizontal break in some mortar

2) systematically hunting around while twitching its antennae and wings on a very gravelly, super-fast draining rockery surface

...both in a garden environment in London. (Albeit a very green one.)

[Action_Man]

It could be a Pompilid looking for spiders to take to its hole in the rockery ...

[crazylilthing]

Originally Posted by Action_Man

It could be a Pompilid looking for spiders to take to its hole in the rockery ...

Ah, very interesting. I have looked up some pics and that makes sense. It has the curly antennae of the one I googled, but haven't seen yet if it has what appears to be a characteristic spur coming out of one of the leg segments.

I saw one fly right into another crevice in a wall, today, one that was obviously hazardous to most insects as surrounded by web debris. I waited 5 minutes but it did not re-emerge. I wonder what it was doing?

[Geoff F]

If it is a Pompilid, Anoplius nigerrimus is all black although rather small, say 10mm max, most of the larger species have a patch of red (or other colour) on the abdomen but this is sometimes difficult to see.

And there are quite a few members of the Solitary Wasp family which could also possibly fit. It really needs some clear photos of the wing patterns to narrow things down. Yes, I know, this is very difficult to achieve.

Is there earth behind the masonary? I have recently seen A. nigerrimus digging burrows in a stony bank and they often dig behind stones for more protection to the burrow. Blackbirds try to dig out the more exposed burrows.

[crazylilthing]

Originally Posted by Geoff F

Is there earth behind the masonary?

No, it's a gap in the mortar between two courses of brick with nothing on either side.

The other wasp, in the rockery, now habitually returns to a precise spot in a tiny depression in the soil/gravel. It appears to be chewing the soil before flying off. It has been doing this for at least 4 days.

I will check out the species you suggest and report back. Thanks for all the input so far, Geoff.

[Geoff F]

It does sound strange behaviour. I just wonder if it is catching prey inside the cavity and taking that to it's nesting burrows in the garden. Nesting in building gaps is more like some of the mining bees.

I have recently been watching some Mason Wasps, Odynerus spinipes I think, constructing burrows by chewing soil and erecting a 'chimney' around the burrow entrance. I will post some photos sometime in the future.

Some of the Digger Wasps, like Crossocerus sp. for instance, are black and behave in a similar way, also Trypoxylon as you previously mentioned and according to my literature can nest in hollow stems, woodworm holes and any narrow cavity.

I am not sure if they carry 'best quality building materials' from a suitable source to the nest site. But, once again, this sounds more like bee activity. Perhaps one of the experts in these species will be able to enlighten us with an explanation.

[crazylilthing]

Thanks for your interesting and helpful reply, Geoff.

Originally Posted by Geoff F

IPerhaps one of the experts in these species will be able to enlighten us with an explanation.

Well, I, too really hope one of the experts in these species does see this as I'm deeply intrigued and want to follow this to the end until I find out.