Ants on Milkweed

[tartandtiny]

My milkweed plants are infested with 1/2 size brown ants. Are they a danger to monarch eggs & larve? What should I do to eliminate them?

[Paul Cherubini]

Sometimes ants eat monarch eggs and small larvae, especially at night. But other times I see larvae and ants coexisting on the milkweed plants. So it's hard to generalize, but most of the time ants WILL eat monarch eggs and small larvae.

About the only effective solution I know is to remove the monarch caterpillars as best you can and then spray the milkweed patch with Ortho Malathion Plus insecticide (available at Walmart and Kmart) diluted 2 teaspoons per gallon of water. 10 minutes after spraying, rinse the treated plants off with plenty of fresh water from a garden hose. When the milkweeds have dried off, put the monarch caterpillars back on the milkweeds. This treatment also gets rids of earwigs, aphids, spiders and other predators of monarch eggs and caterpillars.

[Mona Miller]

Sometimes ants eat monarch eggs and small larvae, especially at night. But other times I see larvae and ants coexisting on the milkweed plants. So it's hard to generalize, but most of the time ants WILL eat monarch eggs and small larvae.
About the only effective solution I know is to remove the monarch caterpillars as best you can and then spray the milkweed patch with Ortho Malathion Plus insecticide (available at Walmart and Kmart) diluted 2 teaspoons per gallon of water. 10 minutes after spraying, rinse the treated plants off with plenty of fresh water from a garden hose. When the milkweeds have dried off, put the monarch caterpillars back on the milkweeds. This treatment also gets rids of earwigs, aphids, spiders and other predators of monarch eggs and caterpillars.

Make sure you read pesticide label directions and follow the directions carefully because doing otherwise is against the law and can also cause problem for you and the environment. Spraying on pesticides and washing them off can cause potential problems with runoff and ground water pollution.

http://www.epa.gov/nps/MMGI/Chapter2/ch2-2d.html
Polluted Runoff (Nonpoint Source Pollution)