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Plant Pests: Aphids, Mealybugs & How To Control Them

If you have plants, they'll get infested with insects at some point. Here I talk about aphids, mealy bugs & how to control them. Find pictures to i.d. them so you can take action.

a collage with 3 different plants infested with aphids the text reads Plant Pests: Aphids, Mealybugs & How To Control Them.

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

orange aphids on the back of a hoya leaf

Different color aphids on the underside of my hoya leaf.

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.

greens aphids on a mint stem     

Ants hanging out with aphids on my Mojito Mint stem.

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

a bad infestation of mealybugs the stems are covered in white

A bad infestation of 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.

mealybugs in the nodes of a succulentMealybugs love succulents. Here you can see how they gather in the nodes. The black spots on the leaves are that fungus.

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 & neem 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 concentratehorticultural 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 on a butterfly weedOrange aphids covering the stems of Butterfly Weed.

Things to know about plant pests and controlling them:

* 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.

*It’s very, very, very important to spray the undersides of the leaves thoroughly. That’s where these pests hang out.

*Be sure to inspect any new plants you bring home to make sure they’re not carrying any pests.

*The same goes for plants which have summered outdoors. Check them for pests before bringing them in for the colder months.

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,

 

 

 

 

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16 comments:

  1. If the mealy bugs are in the root how do you get rid of them there?

  2. Hi Sylvia – I’ll be touching on that in a video & post soon. I’ve dealt with them a couple of times. Here’s what I did: remove the plant from the pot & shake off as much soil as you can. Put the infested soil in a plastic bag & get rid of it. Dip the roots in warm to hot water (hot enough to kill the mealys but not the roots) with a few drops of mild soap. Repeatedly dip them. Pot the plant into fresh soil. Nell

  3. I like how you conversation, Nell.Thanks alot

  4. Thank you Linda! Nell

  5. Just sprayed my mealybugs with water so they’re gone for now but I’m sure they’ll be back … will try rubbing alcohol next time! Thanks for all the work you put into sharing your expertise 🙂

  6. Hi Jen – As I said, plants & pests go hand in hand so I’m sure you’ll see them again. I’m always happy to share! Nell

  7. Item #3 – you say “need” oil… I think you might mean NEEM ?

  8. Susan – Oh yes, that’s for that! I’m changing it now. At least a few lines down the links go to neem oil. Nell

  9. great informations ….. seems garlic and neem extract will do the work….my potted plants are infected secverly

  10. Thanks for this informative post! I caught some mealybugs early on and sprayed the staghorn plant down and then literally just went through, leaf by leaf, and scraped off any little ones I could still see with my fingernail (yes, gross, but the kitchen sink wasn’t strong enough to get many of them apparently).

    The fern doesn’t seem to be too badly damaged yet, but I am wondering for future reference how you get rid of the black fungus/residue. Do you just have to remove leaves/sections with that entirely? Or is it something you can spray/wipe off? Or?

  11. Hi Nazir – Thank you. I’ve heard that garlic oil works but Have never tried it myself. Thanks for sharing that. Nell

  12. You’re welcome Sonja! The black residue is due to the honeydew secretion by the pest. Once you get the pests under control, you can easily wipe off the residue off the leaves with a damp cloth. Nell

  13. Hi Nell,
    I sprayed my succulent with neem oil with water( followed the manufactures instructions) but now my succulents have unslightly spots on them. How do I get rid of them ?

  14. Hi Jean – it might be spots from from too much moisture. Once they’re spotted, you can’t from that, you can’t get rid of it. Nell

  15. If you blast them off with the water hose, won’t they just climb back on the plant?

  16. Nick –
    They usually don’t. They love the fresh growth that pops out in Spring. If they show up again in summer, I just hose them off again. Nell

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