Plant Pests: Aphids, Mealybugs & How to Control Them (2024)

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Plants and pests go hand in hand. They are by no means a match made in heaven; but chances are that if you have plants, they’re going to get some sort of infestation at 1 time or another. There are so many different insects which are specific to certain plants and/or regions. I’m going to cover the common ones that I’ve seen most often infest plants, both as houseplants and in the garden. Today I’ll be talking about aphids and mealybugs and how to control them.

Both aphids and mealybugs are soft-bodied, sucking insects. They slowly suck the sap out of a plant which over time weakens it, stunts the growth and deforms the flower. You can liken sap in plants to blood in animals. The sap contains sugar which the insects love but can’t fully ingest and it oozes out on the plant. You might also notice a black mold-like substance appearing on the leaves. This is actually a fungus which grows on the sugar. It can ultimately damage the plant too. Ants flock to an infested plant – they’re after the sugar too.

Aphids

I’m starting with aphids because they seem to appear out of nowhere in the spring. 1 day you can see 5 of them and 5 days later there seem to be 500. They come in a variety of colors including green, orange, black, brown, white, gray and even pinkish.

Different color aphids on the underside of my hoya leaf.

My hoya topiary had orange, grey and black aphids, my mint had green aphids and my grapefruit tree has black aphids. And they’re all within feet of each other! Aphids love fresh, new growth and tender stems. They, like most plant pests, like to hang out and feast on the underneath leaves where it’s a bit more protected.

Mealybugs

Mealybugs move slower than aphids. They can be found on every part of the plant, even the roots. They especially love to hang out in the nodes and are a common pest of houseplants.

If you see something which looks like white cotton on your plants, then it’s mealybugs. That’s the white trail that they leave behind. Growing up in New England we had a 3′ Jade Plant growing in our greenhouse. It would get mealybugs and I would dab them off with a cotton swab dipped in rubbing alcohol and water. I must’ve really loved that plant!

How To Control Aphids & Mealybugs:

1)Predators.

Release ladybugs or lacewings in your garden as a method of control. Lacewings devour soft bodied insects much faster than do ladybugs. This obviously isn’t a viable solution for your houseplants!

2)Spray with water using the garden hose, kitchen or bath spray.

This is the method I fall back on. You want to gently blast off (no fire hose action here please) the pests & their eggs. I illustrate this method in the video on my hoya. The spray in your kitchen or bathroom will be suitable for your houseplants if you don’t have access to a hose outdoors.

3) Insect killer sprays.

I don’t use chemicals so these are considered to be “natural controls”. They include: horticultural oil, insecticidal soap & need oil. Most plants can be sprayed with these but just check 1st. You can do a little research & see which would best for you. Here are some options: insecticidal soap ready to use, insecticidal soap concentrate, horticultural oil ready to use, horticultural oil concentrate, neem oil ready to spray & neem oil concentrate. This 1 lists itself as a houseplant & garden insect killer.

4) Homemade spray recipes:

Here’s the way I’ve always made an soap/oil spray: Mix 1 tablespoon mild dish soap or Dr. Bronner’s, 1 tablespoon vegetable oil & 1 cup water. This works on mild infestations. Here’s what I’ve used to get rid of mealybugs: Mix 1/4 cup rubbing alcohol with 1 cup of water. You can either dab it on the mealybugs with a cotton swab or spray it on. Rodale’s, a source for living naturally which I’ve known about & respected for a long time, has a recipe for this natural pest spray with garlic, onion & cayenne pepper.

Orange aphids covering the stems of Butterfly Weed.

Things to know about aphids, mealybugs & their control:

* Aphids especially love fresh growth. Mealybugs love to hang out in the nodes & crevices. Both can be found on the undersides of the leaves.

* Both have soft bodies so they’re easy to control early on.

*Which leads me to: control these pests as soon as you see them. Once the infestation gets bad, they’re hard to get rid of. Your plant may not recover.

*Ants are after the sugar residue left behind by the aphids & mealybugs. Once the insects are gone, the ants will be too.

*The leaves of the plant can get sticky – that’s caused by the sugar secretion. You might see a black residue (the fungus) appear – you’ll want to get rid of that too.

*If you choose to spray as your method of control, you’ll need to repeat. Follow the instructions on the bottle as to how often. A homemade spray you can repeat every 7 days. It might take 3-4 rounds to control the pests.

Make sure the plant isn’t stressed (ie bone dry) before spraying. And, don’t spray in the hot sun. Hopefully, your plants never get aphids or mealybugs but if they do, you can now identify them and take action.

Next up in the plant pest series: spider mites & whiteflies.

Happy (pest free) gardening & thanks for stopping by,

Nell