Ants are little bastards to kill. I’ve had the bad luck to repeatedly live in houses that were seemingly built on top of ants nests, and have tried everything, Most ants are either immune to or avoidant of those liquid ant baits by now. In fact, they swiftly learn to avoid anything that’s toxic to them.
Nicotine does work. And works best of all if you find their nest , make a borehole in the middle and pour a load of reasonablty high % juice into it Try daintily sidestepping that lot, you little bastards! I can’t proffer a formula. I save assorted failed mixes all mixed together in a bottle for that sort of purpose.
I wouldn’t worry about killing the bees if you’re using nicotine to kill bugs indoors, nor if you use it oudoors in that fashion. Just don’t spray your garden plants with the stuff.
I 've also found this effective:
//www.amazon.co.uk/Dethlac-Insect-Lacquer-250ml-486698/dp/B00QXD2ZRY/ref=sr_1_1_sspa?keywords=dethlac&qid=1558231257&s=gateway&sr=8-1-spons&psc=1&smid=A2AE65YK30HBAQ
that said, if you leave a bit pf your floor/woodwork unlaquered, ants are likely to find their way through your kitchen and onto your unlaquered living room carpet, eventually. a few hundred dead workers will not deter them . they’ll just learn what route not to take.
As for DE: yeah, do be very carefu to buy food grade stuff. When I experimented with DE, I decided to cut costs and buy stuff that was marketed as safe for treatung animals, reasoning that its safe for animals , it must be safe for humans. wrong. It really screwed with my respiratory system for weeks! And it’s really hard to get rid of, if you get it onto furnishing or carpets. if you hoover it up, the hoover just blows it out into the atmosphere.
I think “Safe for animals” just means “Animals don’t have lawyers”
After that, i bought “food grade” but I haven’t dared use it.
EDIT: reponse to OP., not Srksfly. Sorry, i used the wrong button again