Need advice re: carpenter ants

western mt -

We definitely have carpenter ants in our home.
I possibly found main nest in a douglas fir, about 1/4 mile away.
We've been using Terra bait traps for a few weeks inside.
There are a few locations where I found them coming in from the walls - under a window, and a door jam, for example.

I found two outdoor areas where they seem to be entering. I cannot find their entry point, only the region. I need to do something of a barrier - to prevent more from coming in.

I am very worried about ecology-effects.
I want to avoid diatomaceous earth - as I don't want to kill other insects.
I'm also worried about effects on a local toad spp (western toad - endangered where i live).
Especially for the outdoor areas, I'm worried about food-net effects of others eating the baited ants - birds, spiders, toads, etc - will they get sick if they eat ants baited with Terra (borax)?
Haven't found research about this - any recs?

For the colony that lives in our home - what should we do? I don't  have a sense of where the nest is. What least-toxic options are there?

thank you!

From Google http://www.idph.state.il.us/envhealth/pccarpenterants.htm#:~:text=Carpenter%20ants%20are%20one%20of,a%20threat%20to%20structural%20integrity.
'Carpenter ants are one of the most common household pests in the Midwest. Besides being a nuisance indoors, these ants damage wood by hollowing it out for nesting space. While carpenter ants do not eat wood, large colonies can be destructive; however, are more of a nuisance than a threat to structural integrity.'

I would try using vinegar to see what happens.

Or used dish water as both work for me on most ants.

i would clean the inside of your house where they have been with vinegar, or mint essential oil in water, or in vinegar-- something stinky to discourage their chemical trail.

outside, in that general area where you think they're coming in.... I would stir up the dirt-- rake it, stomp on it, do whatever you can to harrass them. Dump dishwater, like Anne says. Hose it down. Keep in mind they may move into your house more, so stay on your guard. But harrass them and they'll figure out there is somewhere better to be, and maybe you'll figure out how they're getting in in the process. Hopefully they're coming from that nest you found and they'll decide, after getting whacked around, to go in a different direction (keep an eye on your outbuildings!!).

(I also am not thrilled with borax due to its effect on other animals).

I wouldnt assume the Douglas fir 1/4 mile away is where the ants in the house are coming from. They can have satellite nests too, sometimes right in or around the structure.Since you're seeing them around the window and door jamb, I'd probably start there. Look for any old water damage, soft wood, failed caulk, condensation, anything that stays damp. Another thing that might help is going outside after dark with a flashlight and watching where they actually travel. If you find a steady trail, follow it in both directions if you can. That can tell you a lot more than trying to guess where the nest is. Also keep an eye out for coarse sawdust or little piles of debris around trim, siding, windows etc. Carpenter ants sometimes push that stuff out of the nest and it can give away where they're working. Personally I'd try to figure out if there is a nest in the house first before worrying too much about making a barrier outside.

i had a big ant issue in my kitchen, and tried an assortment of things from vinegar to essential oils to dilute boric acid

a fairly benign way to stop them is to spray them with a water dilution of bicarb soda in water. insects seem to absolutely hate it, as i think the strong alkalinity of the bicarb effects them and bicarb is like an abrasive like DE but not as harsh, and i know its also effective against fleas and have even used it to stop the most horrible bugs in cheap hostels-bed bugs! i believe its a benign substance for other species too. you could also try experimenting with trace amounts of pyrethrin which i believe comes from daisies, which i put on the sill of the wall to stop the trail of ants because the spray wasnt enough . im not sure if you could make your own concoction by soaking the right kind of daisy in cheap cooking alcohol etc to make the concoction, and make your own pyrethrin tincture