How to Get Rid of Milkweed Aphids on Your Milkweed Plants
Does the image above look familiar?
Seeing the little yellow bugs swarming your precious milkweed is one of the most disheartening things you'll see when starting out your native plant garden.
No matter how many you remove or squish, they just keep coming back, sucking the life out of your poor milkweed plant. AND infestations of these aphids have shown to decrease milkweed seed germination from 90% to just 20%!
So what can you do?
That was my mission this summer as the Swamp Milkweed in my rain garden became covered in these yellow pests from the flowers all the way down to the base of the plant. It was bad.
Interestingly these bugs are that they are invasive pests that likely originated in the Mediterranean and thrive on the sap of the Oleander. Oleander shrubs are popular ornamental, flowering shrubs that do well in subtropical climates, but are grown pretty much around the country during the summer.
As with many oriental plant pests, the Oleander Aphid found similar food in native US milkweeds, sucking the sap from their leaves and leaving behind a sticky substance called Honeydew. Ants typically hang out around these aphids, as they enjoy the sweet taste of that Honeydew.
Unfortunately, since Oleander Aphids are invasive, they can infest a patch of milkweed pretty quickly if not handled early. Through my research, I found that there are two main ways to get rid of them:
1. Neem Oil
2. Introducing natural predators
Neem Oil is a natural pesticide that originates from the Neem Tree and interferes with insect feeding behavior AND sometimes prevents insects from laying eggs.
I DO NOT RECOMMEND NEEM OIL FOR MILKWEED
Neem Oil is incredibly effective on most insect infestations and is organic. However, it is also effective on Monarch caterpillars, which you'll probably want in your garden.
Save Neem Oil for non-host plants.
Introducing Natural Predators
Like most insects, aphids have natural predators. Introducing parasitic wasps is one option, as they will lay eggs inside of the aphid nymphs and those eggs will hatch into hungry larva that eat their way out of the nymph. Pretty gruesome, but also satisfying in a way.
The absolute best predators I've found for these aphids are Ladybugs and Lacewigs
I'm not exactly sure where I read online, but I came across this obscure product called, PredaLure from ARBICO Organics. Supposedly, these Lures were supposed to attract both Lacewigs and Ladybugs to attack the aphids and eliminate them.
I was skeptical, but it was only $10 for 2 Lures, so I tried it out.
And I was freaking amazed at the results.
I opened the packages and they smelled similar to a citronella candle, so I knew there was at least something there. I tied one Lure to each milkweed plant (likely too much) and waited for about a week.
Between 1-2 weeks I noticed fewer and fewer aphids, but didn't see any ladybugs, or at least I thought I didn't. I did see these weird, long and spiky insects crawling around on the leaves of the milkweed. Little did I know, I was looking at Ladybug larvae!
About 1 week after that - all of the aphids were completely gone! Plus you could see a bunch of Ladybug pupae and larvae everywhere.
Update: Insecticidal Soap
I'm a pretty avid follower of Homestead and Chill and noticed that they have a great guide to how to make your own insecticidal soap! I haven't attempted this just yet and won't be able to test efficacy for another few months, BUT, thought I'd add their recipe below so you can try for yourself:
Homemade Insecticidal Soap Recipe
Combine 1 tablespoon of liquid soap per quart of water. Mix only what you will use that day. That's it!
Spray using a gallon pump sprayer or squirt bottle for smaller plants.