Who knew that ants loved roses as much as I did, if not more. As a rose person, this is heartbreaking.
But it is also important to make sure the ants aren't harvesting aphids on the roses.
- Ants target other sap-feeding insects on roses, not just aphids.
- Try Tanglefoot around the base of the canes.
What I have found out is that you want to kill the hive.
The reason is that species of ants that attack roses aren't going to let you have roses.
DE is somewhat effective against ants, but only ones that cross your DE line. A borax trap will let you do that - you make a sugar syrup and dissolve borax in it, set it out in saucers or shallow dishes, you can soak cotton balls in it and set those around too. The ants slurp it up and take it back to the hive and feed it to the queen and hive workers.
You also won't see immediate death, and there's a big old hive to replace the ones who were killed. Soap sprays have the same problem, they'll kill only individuals that are hit.
While killing the whole hive seems extreme there isn't much else you can do.
This is gardening.
And while it seems to go against it. In fact when you make a garden, you're creating something that is intrinsically artificial. There's nothing "natural" about a garden because a garden, by definition, is an arbitrary grouping of only those plants chosen specifically by humans to inhabit that space.
This is also why, due to the unnatural nature of the guarden, the ants decide to eat roses instead of their natural food such as dead (and living) detritus on the ground.