Created by Connie Gladding
Master Gardener Volunteer
Be on the lookout for these yellow polka dots on emerging plant sprouts in your butterfly gardens. It seems almost overnight they appear. Especially scout your milkweeds. The milkweed stems, undersides of leaves, and top tender growth may be covered with yellow polka dots, aka, oleander aphids, (Aphis nerii).
What are Aphids
Aphids are a common pest on milkweeds, such as butterfly weed, Asclepias tuberosa. The aphids have piercing-sucking mouthparts and harm plants by feeding on the sweet sap inside of plants. Aphids excrete large amounts of honeydew which is a sugary liquid made up unused plant sap and waste. A black fungus called sooty mold usually takes up residence on the honeydew. Ants also feed on honeydew, so if you see ants, look closely for aphids.
Fun Fact: Aphids are all female, born pregnant, and give live birth.
What to Do
DON’T DESPAIR – aphids can be managed and without harming caterpillars and beneficial insects, the “good bugs”. The “good bugs” keep pest infestations under control naturally. A common ‘good bug’ is the lady beetle. Both the adults and larvae of lady beetles consume aphids.
Encourage beneficial insects to visit your butterfly garden by planting a wide variety of flowering plants with year-round pollen and nectar sources.
Here are three easy methods to manage an aphid infestation:
- Spray a strong blast of water to dislodge aphids off of the plant
- Let the beneficial insects fight the infestation
- Treat with a horticultural soap following the label instructions.
Notice that using pesticides are not your first option. Pesticides may kill the aphids but also the beneficial insects. Lastly, don’t fret over small infestations. Treat only when there is a heavy infestation causing damage to the plant rather than just for aesthetics.
Where is More Information
To learn more about aphids and beneficial insects that help to manage infestations see: