boric acid in sugar syrup might work, depending on just what they are - can't imagine they're actually after the 'barb, I'd think you might just have created some desireable condition for them when you planted

Bill

Since about the only problem there is with Rhubarb is crown rot those ants may simply be cleaning up from that problem. I have not ever seen ants bore into any plant, although they will go in after some other insect pest. Check your soil and moisture levels around those plants.

I have the same problem. There are no other insects, just massive ants that are eating holes in the rhubarb leaves and tunneling throughout the stalks. Plants look horrible now. There was no crown rot or any other issues, this has gone on for 3 years in a row! Help!

I have the exact same problem as above and just planted my plant last year, they were doing great and now the ants are tunneling throughout the stalks. There is no crown rot or other issues around my plant either. Please Please someone help??????

If you Google 'rhubarb and ants' this topic comes up with alarming frequency. Apparently some ants (have no idea which species) will tunnel into rhubarb stalks and suck out the tart juices. It is also more common than not to have ants establish hills or nests under the rhubarb root system and disrupt its growth. Odd, because the same search will also turn up recipes using rhubarb leaves to ward off or deter ants on other plants!

I have no answer for you other than to use whatever ant control product you feel comfortable with and that works. Or you could brew up some rhubarb leaf soup and spritz the plant down regularly to send the ants elsewhere.