We’ve noticed we don’t find monarch caterpillars on milkweed plants that have ants on them. We’ve also noticed if ants start coming on a plant with a caterpillar on it, the caterpillar disappears. It doesn’t seem to show up on a neighboring milkweed plant either.
I’m wondering if anyone has a way they keep ants off these plants so the caterpillars can continue their life cycle in peace.
There’s a YouTube series about monarch butterflies by a guy called Mr. Lund who experimented with using powdered cinnamon at the base of the plant to discourage ants. It does require regular reapplication. Could be worth a try?
Usually the ants are there because they love the sap that aphids make so if there are ants, there are bound to be aphids. You can get rid of aphids by crushing them with your fingers (gotta check to make sure no first instar caterpillars are hiding nearby) or hosing them off the plant.
I’ll have to try the cinnamon next year. I ended up sprinkling diatomaceous earth around the bottom of it and that seemed to help. But I’m not sure how often a monarch caterpillar might move to another plant so I was worried the DE may harm them too.
Some of the plants do have aphids, but not all my plants with ants on them had aphids (at least that I could find). I know ants will sometimes carry aphids, so maybe they were scouting out new plants?
The caterpillars might wander if food is low on the plant or when they want to make a chrysalis they often crawl off the plant.
Are your plants in the ground or in pots? Just curious cause I’ve had aphid problems across all of mine but never ants since I grow mine solely in pots.
Argentinian ants are used to irrigation. Stopping irrigation can reduce amount of nests.
You could also try to kill the aphids on some other host plants. Or try to move your trash containers