Are aphids on milkweed harmful to monarchs?

No, aphids eat the milkweed plant, not monarchs! Ants that tend the aphids can sometimes attack small caterpillars on the plant, but the aphids themselves do not harm monarchs. Additionally, the presence of aphids is a good sign that your plant or habitat is likely free of chemicals and pesticides. However, if you want to remove aphids, there are a few ways to do so. The simplest method is to squish them with your fingers. If there are too many to squish or you prefer a different approach, spraying a soapy mixture directly on the aphids can help reduce their numbers. Below are a couple of recipes you can try. Just remember to always check your milkweed for monarch eggs and caterpillars before managing for aphids.

Spray Solution from Monarch Watch and Taylor Creek Nursery

• 1 part (e.g. 1 oz) Blue Dawn
• 1 part Isopropyl Alcohol
• 1 part white vinegar
• 128 parts (e.g. 1 gal) water

Spray Solution from Conservation Blueprint 

• 1 tablespoon of liquid castile soap (adjust as needed)
• 1 quart of water