Wasp Problem at Apex of Fascia

[MoonMan2]

Noticed yesterday loads of wasps entering and exiting my single floor extension, at the apex. They are entering via what appears through a gap in the cement between bricks OR perhaps it is the final brick (not cemented to an adjacent brick): I can't see because of fascia 'hooded' over the bricks.

The picture below is a bit misleading; there are actually dozens of wasps going in and out of this gap/hole every few minutes.

Unfortunately I can't tell if there is a nest within the soffits or in the loft area as I have no hatch access up to the loft.

I have ordered wasp powder, tube control bulb and a wasp hood. I will go up ladders and apply puffs of the powder at the entrance - does this sound like the most appropriate course of action?

Next thing I noticed is that on the front and rear of the extension, there is silicone between fascia and bricks:

and

But you'll notice there isn't any silicone applied at the gable end. Is this normal? You can see the gap(s) better here:

and

The gap(s) between the brick and fascia varies between zero and about 1cm along its entire length.

Should I (after I get rid of the wasps of course) silicone the gap all along the fascia, hopefully ensuring that this would be the last time I have to deal with a wasp problem? Or is there some reason for this 'gap' and should I just leave it as it is?

Finally; the 'hole' in the cement at the apex where the wasps are getting in, I presume I just point this?

 

[lonner]

You have a nest 100%.
If there not bothering you just leave them.they'll be gone September..

They ted to find ways in,so id not bother trying to block them.


you can treat them with a good wasp killer But you need to get to it,not easy if its in a bad spot inside the roof space.

best to spray it late evening if you can find it.
i had one last year that was massive!! But the wasp nest killer sorted it.