How to tackle this carpenter ant ingress point?

Since moving into a new house about 6 weeks ago, we’ve occasionally seen small black ants indoors. We see about 5 a week on average. They don’t seem to be doing anything specific indoors, i.e. they’re not pillaging the dry goods cupboard. We keep the place pretty clean, food sealed, and we’ve never seen them in the kitchen area.

However, I did discover that there are some gaps in the sealant around one of the windows, and ants are coming and going from there. I assume it’s the same group of ants and some of them are exploring further indoors. Next to the window are some vines with aphids living on them that the ants appear to be quite feeding on. I gather carpenter ants will eat honeydew created by aphids. If I watch for a while, I’ll see the odd ant come or go through one of two small holes in the caulking of the window.

I think these are carpenter ants based on appearance and size. Most of them are around 6-8mm long, but I caught a couple yesterday that measured 9 and 13mm long.

I don’t suspect a large scale infestation because I rarely see them indoors, and I’ve seen no evidence of frass (sawdust expelled from tunnels in wood by the ants).

So, I’m wondering how to tackle this issue. I see three main options, two of them DIY:

1. Use either Borax- or Diatomaceous-earth-based slow-acting powders/ baits around the opening they’re using, with the hopes that those either kill off the colony if I’ve got one inside that wall, or just make the area inhospitable enough that the ants move on if this is just a shelter point for them when feeding on the aphids. In parallel, cut back the vines/ spray aphids to eliminate that food source. Once the ants are gone, seal the holes with pest deterrent expanding foam and fresh caulking.
2. Use fast-acting ant killer like Wilson foaming spray, just pump a generous amount into those holes, give that a day or two to do its thing, then again seal with the pest-resistant foam and caulking, and in parallel try to reduce the aphids.
3. Third option is just get a pest professional in right away.

My worry with #1 is it may just not work and may take a while (multiple weeks?) to determine it’s not working. Reviews on Borax/ Diotemaceous based approaches seem very mixed. My worry with #2 is that the foaming pesticide leaves a lot of ants alive and now sealed inside, forcing them to tunnel out elsewhere, possibly further into the house.

Any thoughts on the above options or alternatives would be appreciated. FYI, I’m located in Ottawa, Canada, in case geography is relevant.

Here are some pictures:

The window – the vines and ingress points are in the lower left corner:

Ingrress points – I’ve only seen ants coming and going here:

Ants tending aphids:

Ant close up – I’m pretty sure these are carpenter ants: