Sorry that you have to contend with chili thrips. Your suffering reminds me of the year after year misery of having to spray religiously, every two weeks, from early May until mid-October for the dreaded rose midge fly.....a serious problem in the Northeast. I found only conventional spraying was effective.....organics failed miserably. If not faithfully sprayed, there would not be one bloom in the entire rose bed after the first flush all season long, nothing but green leaves, no flowers.

Suddenly, without any tapering off, with the spring of 2025 season things starting as usual....I began spraying preventatively in mid-May, but it soon become apparent that there was no midge damage occurring (even with spraying about 5-8% damage was always seen....an acceptable level), nowhere to be seen. I stopped spraying, and sure enough, not a speck of rose midge fly damage anywhere. It's been totally clean this year too. Amazing! It has to be Divine intervention, because such a switch is unheard of locally.

Back to your dilemma.....can you spray with a conventional systemic, or with a soil drench for chili thrips?

Moses.

I don’t know if mine are thrips or chili thrips. I just know that spring and early summer is when I battle the thrips horribly here. I’ve used so many gallons of Spinosad that I’d embarrass myself if I’d kept count. This year I ordered the biological insects to battle them and actually had better success than I do with spraying.
At this time of year, I don’t seem to have them at all, which is a huge relief to me.

I don't have chili thrips nor midge in my heavy clay & zone 5 NW Chicago. But I have Japanese Beetles that lay eggs in the soil from late June to early August.

I root roses and mail them out to donate 100% of the proceeds to charities. I follow the procedure to prevent insect transmission across states. I strip off ALL soil from my rootings, then submerge the entire plant in 4 cups of water mixed with 1 TBS. of insecticide soap.

Web info. said chili thrips cannot be killed by soaking in water alone, insecticide soap has to be used. Insecticide soap is sold cheap on Amazon for $10 per 32 fluid ounce (4 cups).

Chili thrips can't survive my cold winter at -20 F below zero, and other species of thrips are lessened by my cold weather.

Green Lacewings and Lady bugs are predators to reduce thrips. Green lacewings are attracted to plants such as dill, fennel, cilantro, goldenrod, yarrow.

Lady bugs are attracted to dill, marigold, yarrow, sweet alyssum, calendula, purple cone flower,

I didn't have thrips in the years which I planted lots of dill & marigold, sweet alyssum in my back garden.

Before 2005, my garden had tons of yarrow (very invasive), we had lots of lady bugs back then and I never saw any thrips back then.

This year I have lots of calendula & purple cone flower in the front garden, and I don't see the regular thrips there, but I see regular thrips in my back garden.

Next year I will plant more sweet alyssum to attract lady bugs. Also dill to attract green lacewings (aphids lions). Never have any aphids with dill planted between roses. Below is sweet alyssum in my garden:

Below is yellow Calendula in my garden, lots of ladybugs in my front garden to wipe out the regular thrips:

I have been deep in the chilli thrip fight and am finally winning.

This is what has worked for me:
First, I trimmed off all thrip affected growth, which nearly killed me to do. Lost so many buds and new growth. I bagged it all and tossed it.

Next, spinosad, I apply at night because of the heat and to protect the bees. Skip the stuff in a spray bottle and get the Conserve which is much stronger. It’s expensive but you don’t need much.

I sprayed, then the following week sprayed insecticidal soap on all the new growth. The week after that sprayed Conserve again.

Sticky blue traps

Beneficial insects, especially nematodes

But what I think has made the most difference is overhead watering. Every day I go out and hose them down with a pretty strong stream of water—I use a hose wand. I make sure I wet the soil throughly and spray down the entire plant and underneath the leaves. I do that during the day so it doesn’t sit for toooo long. It is causing more black spot than I’d see in the heat and dry but I’d rather have blackspot than the thrips.

My plants are finally rebounding with this routine. They truly are nasty buggers.

Next year I will be planting more companions for the roses to harbor other beneficial bug friends.

Like Claudia I’ve used beneficials. Last year I bought pirate bugs and that really helped. This year I didn’t have any thrips, not sure why, could have been the awful drought we had here in Colorado.

I have been fighting chili thrips for years . what works for me is watering the entire bush like Otterbon said . And spraying every 2 to 3 weeks rotating Conserve and Bonide systemic insect control .