I have a significant thrip infestation on my cacti.

In previous years, I grew them outside in pots and had no issues. Presently, I have a big sunny, bay window and I have 10-15 cactus growing in a manner which looks nicely ornamental to keep the little woman happy.

Never had issues on the previous outside plants and the two I put in soil outside this year had no thrips. However, I want to find a way to continue my low work. nice looking, inside garden.

So, what to do about thrips? I've never had this kind of problem with a cactus and I am afraid that anything I put on them will get in the plant and stay there due to the slow metabolism. I'm even worried about Pyrethrum.

Help me Mr. Wizard.

Thrips? And definitely not mealy bugs, scale insects or spider mites?

I've tackled some of these things (but not thrips) with blends of essential oils in ethanol/IPA/water mixtures but I'll have to dig around to find some more info if that interests you. My other approaches have included physical removal of the offending critters over the course of days or weeks, spraying or dusting with diatomaceous earth and even simply misting with distilled water, depending on which pest it was. Some also suggest washing them off with a water jet from a hosepipe.

And I've killed off spider mites with a neem oil spray. The main thing with formulating sprays is to be wary of burning the plant if the spray is made too strong. Alcohol burns are unsightly and may present an infection risk at certain times of year.

(IME it's been mealy bugs that go for the indoor plants. GRRRR!)

I've had thrip infestations in years past. The way I got rid of them is to set off a standard bug bomb. Not organic, I know, but no more thrips. These days I use diatomaceous earth to ward off grasshoppers and other small nibblers. Not sure if it would work on thrips but it would be worth a try.

How did you use the diatomaceous earth? I actually have some.



Would definitely be interested. I have a bunch of mint growing and an alcohol infusion of that might work for prevention if nothing else.

Pyrethrum breaks down in sunlight in a few days. Do you think it might build up in the cactus and not get broken down?

This is breaking my heart. I'm loving these babies

https://www.amazon.com/H...-350505539236&psc=1

I use one of these. You puff some on to the tender green tops. Reapply as necessary.

It sure is distressing seeing the tops of really pretty specimens all eaten up, even to the point their growth is stunted.

Thanks.

These are in a difficult set up. To keep the lady happy I set up a grow which will make the logistics of moving and spraying difficult. Winter is setting in, so moving outside temporarily is not an option. I may do that come spring. New dirt, repotting, time outside, I dunno.

I've applied diatomaceous earth with a paint brush sometimes - it depends how meticulous you want to be, and how much time you have spare.

The essential oil blend can probably be found by searching along the lines of "insecticidal essential oils in the garden", which turned up a bunch of results for me just now, including the list below. (Although I got my ideas for the blend by looking in a book. Old-fashioned, I know.)

The list below:
Clove Bud essential oil
Cedarwood essential oil
Cinnamon essential oil
Citronella essential oil
Eucalyptus citriodora essential oil
Fennel essential oil
Geranium essential oil
Lemongrass essential oil
Manuka essential oil
Niaouli essential oil
Patchouli essential oil
Peppermint essential oil
Tea Tree essential oil

I seem to recall using a fair proportion of these oils but remembering where I wrote it down - if I even did - is another matter. One more thing I've used as a contact insecticide is tincture of nutmeg.

I'm also wondering if you could use a slender vacuum cleaner attachment to suck the critters up.

Great ideas. I already have diatomaceous earth and paintbrushes.

Would I sprinkle the diatomaceous earth on the soil as well? Don't they lay eggs in the soil?

Apply sulfur to the tips, then in a day or two spray the green growth liberally with "Captain Jack's Dead Bug Brew"
or a similar spinosadic soap containing product (Captain Jack's is cheaply and easily gotten, and organic).
Sprinkle diatomaceous earth on the soil above roots if you want to be extra careful, though it shouldn't be necessary.

Good luck. Those little buggers sure do suck the sauce out the spikey bois. Can't blame em tbh.

Thanks. Great username. Hard to pick just one fav, but Help On The Way is one.

"Crippled but free
I was blind all the time,
I was learning to see"

I ended up going with Pyrethrum. In the spring, I will take them outside and repot. Thrips, by all accounts, are less of an issue outside.

When do I retreat? Two weeks?

I have an important follow up question.

I treated with Pyrethrum, then followed up in two weeks. It worked a charm. A surprising amount of new growth for winter is nice and green and healthy.

Now, how about ingestion.

I've used Pyrethrum on garden vegetables and eaten them before. Pyrethrum is actually toxic to humans, but breaks down in sunlight in a day or three. I'm worried about how that might be different in cactus. Wondering if a window grown cactus with it's slow metabolism might store the Pyrethrum inside it somehow away from the weaker sunlight.

Also, I'd be concentrating it.

Anyone used Pyrethrum on Pedro and consumed? Any thoughts?

https://en.wikipedia.org/wiki/Pyrethrin#Toxicity

I don't think pyrethrins count as systemic pesticides, so washing should get rid of most of it. Use soapy water or alcohol.

If you're still concerned about residues, the CIELO extraction would be a sure way of removing practically all of the remainder.

Ah. Good answer. However, I did treat the soil. (read that you should) So, could some have been taken up?

I don't know, but even if it did, Pyrethrins don't contain amine groups and should not be picked up by an extraction TEK such as Kash's A/B or CIELO