Indoor pest control: first attempt

Some of the plants that are overwintering under the grow lights indoors have pest problems every year. Whiteflies, aphids, mites, scale, mealy bugs, and fungus gnats are the culprits, and the first outbreak is happening now: mealys and aphids.

I've got two small elephant bush (Portulacaria afra) plants under the lights, and their succulent leaves and stems are apparently the choicest greenery on my table right now.


I always notice the mealy bugs first on this plant. I never see them when the plants are outside, but as soon as they come indoors these soft, white critters appear.

They almost exclusively stay at the joint between the leaf and the stem...

...while the aphids roam all over the plant -- under the leaves mainly.

Aphids are more rare here, as I don't see them every year. The mealys though, I know them well.

I knew there were aphids from the sticky spots on the leaves:

Normally I would mix up some fresh insecticidal soap, douse this plant every few days, and that would take care of all of these soft-bodied juice suckers. The elephant bush seems to be sensitive to the soap spray though, if I remember correctly from previous experiments.

So I'm going to take a different approach with these this year: a systemic pesticide.

(Note that just before posting I remembered that I have tried this before, but don't remember how well it worked.)

I'm not one to typically use this kind of poison in my garden, but I have it around to help combat mites on some of my bamboos. I'll give it a try here and see if it works on these pests. It should...

It's not recommended to be used indoors.
It shouldn't be applied to plants that produce food.
It should not be used more than once a year... wow, lots of restrictions.

You should always be concerned about these chemicals since they're so potent. Almost 99% of this bottle is "other ingredients" (which is mostly water), and since you have to dilute this severely before using (768:1), you end up with one part active ingredient to 76,000 parts "other" (water). Wow.

Since the plants I'm using it on are in tiny pots nothing close to gallon size, I just estimated how much to mix into a half gallon of water. I used old jar lids to catch any runoff, as that's apparently the reason this shouldn't be used indoors (directions say that you can bring containers indoors after all excess water has dried).

I'm not sure how long it will take before results show. If I don't see the bugs dead in a week, I think I'll apply more. I know it says not to use more than once a year, but I assume that's to avoid soil contamination -- since these are pots multiple applications shouldn't matter.

If even that doesn't produce results, I guess I'll need to use the insecticidal soap even though it may hurt the plants. I know for sure that these pests are causing some harm, and they'll soon spread around the table...

At least the grasses are immune to any pest problems.


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Steve Lau  – (December 27, 2013 at 8:50 AM)  

I've found that insecticide soap won't kill all the aphids so they'll just repopulate, but miticide will wipe them out right away.

Gerhard Bock (Succulents and More)  – (December 27, 2013 at 11:54 AM)  

I'm extremely familiar with both pests. That Bayer products works very well outdoors; I've never used it on houseplants but I don't see why it wouldn't work.

I typically spray mealybugs with undiluted rubbing alcohol, but some plants might not tolerate the alcohol too well. You may want to experiment.

Steve Lau  – (December 27, 2013 at 2:05 PM)  

Another thing I have found that works pretty well is keeping all the houseplants in an area that is cooler, around 40-50F through the winter, and so far I haven't seen any mealy bugs or aphids yet.

Unknown  – (December 28, 2013 at 6:44 AM)  

I detest these pests too. What I normally do is to wash it with a jet of water or simply just wipe them off. The population is greatly reduced or even eliminated. Otherwise introduce some ladybugs. They are voracious eaters.

Alan  – (December 30, 2013 at 8:41 AM)  

Steve: I agree that colder temperatures help keep the pests away, but this is a growing table -- the semi-dormant plants are in the colder garage, but these are warm.

Stiletto: I'm not sure that ladybugs (lady beetles) would be too happy inside my house. Not sure that I'd want them flying around either...

Anonymous –   – (January 4, 2014 at 6:44 PM)  

Steve, I just found your blog, and have enjoyed going thought it! (Wonderful, photos!)
I'm a succulent lover in Ohio, and bring in MANY plants every winter. Mealybugs have been a problem this year. I use Bayer's, too, but the one for Roses, not the one for Trees & Shrubs. I try to apply this before I bring all the plants in each year--I think it's good for 3 mths. With the one for “roses”, you don't have to worry about the once-a-year application. Keep in mind when using the Bayer's, it's ALSO fertilizer, so you have a chance of over-fertilizing your plants. In addition, applying fertilizer in the winter might not be the best idea. Indoors, I use a systemic granules houseplant insecticide made by Bonide. It goes by pot size and is a lot easier to use indoors.
Good luck!

Anonymous –   – (October 2, 2018 at 2:43 AM)  

The elephant bush seems to be sensitive to the soap spray though, if I remember correctly from previous experiments. Bedbug control in Mile End

Ben Stoke  – (October 4, 2018 at 3:14 AM)  

Since the plants I'm using it on are in tiny pots nothing close to gallon size, I just estimated how much to mix into a half gallon of water. Pest Control in Ilford

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