Ants all over milkweed

Hi— hoping I can ask this here. I have several native milkweeds in my yard— thriving yearly. But this year they seem covered in ants. I’m not sure if this means anything but it is different than years past. If indicative of disease, how should I address it?


Ants love nectar. Also, milkweed is a great aphid host, which ants love to farm for honeydew. If you’re worried, find a friendly horned lizard to help :slightly_smiling_face:


Every year my milkweed gets covered in yellow oleander aphids, then then ants move in to farm the aphids, you may have a similar thing going on here! Unfortunately I am not sure how to combat the aphids.


Uhm, why butt in? The aphids are farmed by the ants, and the ants get eaten by woodpeckers…


May not work since it would also get rid of Monarch (Danaus plexippus) eggs, but I’ve had some success getting rid of Aphids (Aphididae) by spraying the leaf-undersides with the fan setting of the hose-sprayer so the force of water dislodges them. Would only do this if it’s a bad invasion and leaves are wilting, though. A few aphids aren’t terrible or worth the hassle.

I observed something similar earlier this month. There were numerous milkweed plants swarming with ants and aphids.

One genus that iNat’s CV suggested was Silky Field Ant (Formica subsericea). The description of this ant included “Workers of this species are incredibly fast” and in fact, they were incredibly fast. I got some video of them and it looks like speeded up video of them running all over the plants.

I think the plant has some aphids and the ants are there because of them, as said before.

I usually see the ants and aphids first, and then parasitic wasps arrive and turn the aphids into mummies. I’ve also seen monarch caterpillars at the final instar eating leaves covered in aphids like it’s the icing on the cake.


In my experience with native milkweeds in my region, you don’t need to remove aphids. They’ll likely be present in copious amounts, but they don’t seem to do much beyond cosmetic harm. I see shrub-sized rush milkweeds with their growth points completely coated in aphids that go on to produce seed without issues.


Mine get really really bad for some reason. The new growth becomes stunted, the buds don’t develop into flowers and the ones that make it turn into sad little seed pods. All the leaves get covered in sooty mold. The milkweed plants did not come back this year unfortunately.


The worst thing is that those pesky aphids are invasive in the US (and here in Mexico too, I’ve even seen them in apocynaceae plants deep in their natural habitats).

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