Jessica Morgan McAtee
If you have been growing Milkweed in hopes of attracting Monarchs, you have probably encountered aphids.
If you haven't yet...just wait, you will.
Aphids are abundant on Milkweed. They are pesky bugs with piercing/sucking mouth parts. Aphids are sap-suckers and are considered pests. They can vector diseases among plants. They drink sugars from plants and then squirt out a shiny or even sooty appearing honeydew that ants are attracted to. When they feed near new growth, leaves can be malformed, twisted, small and sickly. Female aphids can reproduce without males, making them very successful at having exploding populations in short order. They can be yellow, black or brown. Aphids are very tiny, similar to the size of butterfly eggs.
They are often on the stems of plants in large groups. Like butterfly eggs, they can also be found on the underside of leaves as in the photo below.
Beginners often confuse a cluster of aphids on their Milkweed with butterfly eggs. But mama monarchs do not lay their eggs on the stems or in clusters.
Eggs don’t have legs.
When you see a grouping near the stem or under a Milkweed leaf by where it connects to the stem (petiole), it's aphids.
So now what? How do we manage aphids?
Butterflies are insects. Anything that will kill other insects can possibly kill butterflies. Anytime insecticide is sprayed you should be concerned for your butterflies. Routine spraying is not recommended as a best practice because pets, plants, beneficial organisms, insects and humans can be unnecessarily exposed to chemicals.
I don't recommend spraying the aphids with insecticides.
Honestly, I do almost no insect control in my garden. If your plants are suffering from unwanted insect infestations, there are some natural alternatives. First, if at all possible remove the pests by hand (wear gloves).
If that creeps you out, you can spray the aphids with the hose and wash them off.
If certain parts of the plant are heavily infested, you may decide to cut that part off and then dispose of it in the garbage so they cannot relocate to other plants in your garden.
But wait, there's more.
Biological insecticides occur naturally without our efforts. Lady beetles (a.k.a. Ladybugs), lacewings, flies and wasps can all make a feast out of aphids. Ladybug larvae are also voracious predators of aphids. These are beneficial insects and they contribute to a healthy garden ecosystem.
Biological insecticides can be mail-ordered but I think that is somewhat silly since they will occur naturally. For instance, ladybugs eat aphids so some people order ladybugs online for aphid control.
Do you know what else ladybugs eat? Butterfly eggs. So we have to balance out the positives with negatives. Nature has systems that have been in place for longer than we have been butterfly gardening, so I try to leave her to do her job without my intervention.
Another thing I have discovered is that aphids are more prevalent on certain kinds of milkweed. My Giant Milkweed gets aphids, but they don't damage it as much as they do my Tropical Milkweed. That is one (of many) reasons that I use Giant Milkweed more than other kinds.
A final thought on insect control, nature is always in a state of flux. No solution will last forever. Exterminators have to continually spray and natural alternatives will need to be applied repeatedly. Once ladybugs eat your aphids, they may fly to another garden where there is more food. Then, in their absence, your aphids may return. It is always a dynamic landscape and change is a constant. There is a lesson in that.
Jessica Morgan McAtee has been raising butterflies and removing aphids since 2002. She writes about her adventures on her blog and in her books. This post was modified from Raising Monarch Butterflies: In Your Garden.