Flower thrips use many different plants as hosts, and they are highly mobile. Clouds of them can fly in from neighboring fields or yards. I don't think lime sulfur or changing the mulch would have any effect, nor would anything you do now affect next spring's crop of thrips.

What does cause the population to vary is weather and how that affects the population of predators. In my garden, thrips usually peak around the end of the first flush and then recede without my doing anything, as the population of predators such as pirate bugs builds up. However, I haven't had much trouble for years. That's probably owing to the woodsy character of my neighborhood. I haven't used insecticide for years, either.

It is unusual for someone to still have a thrips problem in October. I suspect that will turn out to be a fluke.

Most people just ignore them and maybe discard the varieties that are most susceptible. There are some pale roses that are resistant, for example 'Quietness'. Most of the deeper-colored flowers are hardly affected.You can protect some buds with sections of panty hose, etc., and cut tight buds to bring inside. Or you can spray with spinosad, which is not as hard on beneficial insects as most insecticides. When thrips are bad, start spraying buds as soon as the sepals crack and show petal color. I wouldn't spray flowers that are open enough for bees to enter. Otherwise, spinosad is supposed to be safe for pollinators provided it is applied in the evening after the bees have gone home.

Thanks, Michael--yes, I know thrips in October are unusual, one reason I am so very discouraged. I wish I could just ignore them--someone suggested applying a systemic fertilizer/insecticide now that the bees are less active (I would never do that during the spring or summer) and I'm actually considering it--what do you think of that idea? Maybe if I could get them knocked back on their tiny heels, I could control more easily next spring?

Could someone post a photo of a rose damaged by thrips, please? I think I have them, too. I didn't at first; just a lot of aphids and some awful beetles.I started spraying with a systemic insecticide. It did NOTHING against the beetles, but did get rid of the aphids.The big problem with that was that now, I have thrips! because the aphids supposedly eat the thrips or something.I never saw any damage done by the aphids, either, so now I'm not spraying anything at all to kill insects,not even Neem oil,in the hopes that aphids will come back and get rid of the thrips.So I definitely would advise avoiding an insecticide...a sadder but wiser bart

deranweaver,

The Bayer 2-in-1 fertilizer with Di-syston combines an extremely hazardous pesticide with cheap fertilizer that has an inappropriate analysis. This is a terrible product that shouldn't be allowed on the market. At least two people here have reported having their dogs critically poisoned by it.

The Bayer All-in-1 soil drench with Merit has been reported here to be ineffective against thrips, plus Merit routinely causes outbreaks of spider mites on roses.

Don't buy or use combo pesticide products--they are marketed to hapless newbie gardeners.

Again, roses are only one of many reproductive hosts for flower thrips, so whatever you do to the roses is not going to have much effect on next year's population. Your unusual thrips problem results from the interaction of this season's weather with the population dynamics of thrips and their natural enemies.

bart,

Aphids don't eat thrips, but pirate bugs, certain predatory mites, etc. do, and will usually bring thrips under control. IMO, insecticide is never needed to control aphids on roses.

If flowers are infested by thrips, you can see the barely visible, elongated amber bugs scurrying to hide when you look between the petals. They are less than 1/16". Petal edges will be brown and dry. Flowers will look scratched and puffy.

Hi derannweaver,
I've tried spinosad, and in this garden it was ineffective and useless. I have a very limited number of roses who are attractive to thrips. They are all pale colored and have many petals. On those few roses, in spring, I apply a granular form of imidocloprid around the base of the plant, lightly scratching the granules in, and then I water. The granules are a systemic insecticide that is fairly effective against thrips, especially on the rose, Evelyn. I do this just once a season. These few affected roses are not attractive to bees--in fact I've never seen bees near them. I do have many bees in my garden, including honeybees, bumbles, leaf cutter, wasps, yellow jackets--you name it, and the only roses they are interested in are the singles or those with a few petals. Ballerina is their hands down favorite. If you want lots of pollinators, grow the flowers they love--lavender, Russian sage, butterfly bush, coneflower, mums, asters, hollyhocks (for the bumbles), and others.
Michael, are the pirate bugs you refer to also known as soldier bugs? Like this one? Diane

No, pirate bugs are about 1/8" and decorated with black and white triangles. Here's one pillaging.

Here is a link that might be useful: Minute Pirate Bug

Thanks for the link, Michael. I don't know that I've ever seen a pirate bug. This summer we had a single soldier bug in the center of almost every rudbeckia and coneflower in my front yard for a short time. They were poised as if waiting for some unsuspecting prey to come by. I guess they are a good predator, and they certainly didn't harm any flowers. It was a pretty funny sight, and totally fascinated my granddaughter who photographed a bunch of them. Diane

Thanks, Michealg; I'm pretty sure that's what I have,just because the damage is mainly on lighter-coloured, full-flowered roses.I intend to avoid using poisons,in the hope that things will balance out again. The fact was, I wasn't even trying to get rid of the aphids; I stupidly thought that it (imidocloprid) might help against the beetles (it certainly did NOT!!!) My new anti-beetle strategy is a combination of pherormone traps (placed far away from the rose garden)and screening them out by planting tall-growing things on the fence to help block their "flyways".And, of course, picking them off. It's working pretty well ...
Sadly, the links do not work for me! I don't know why...bart

Thanks--this thread is very helpful. I'm in Augusta, GA and have just recently seen nibbles on some of the new buds coming on my Pearl d'Or. I cut those buds off and disposed of them. Am I correct to suspect thrips? We certainly have had unusual weather this summer so hopefully things will be better next spring, as Michael suggests.

Junco, no, thrips are too small to nibble. They make tiny scrapes and scratches on the petals, causing a bruised and dingy appearance and dry brown edges.

Thanks, Michael. I did some more searching on this forum and read about various insects that might be making the cuts on my buds. Some are vertical on the sides of the buds and some are straight across taking the whole top of the bud. I also see some holes in some of the leaves. For now I am trying to watch closely for a glimpse of what is doing this. I don't intend to spray anything. If I see the insect I will try using a spray of water to knock it off.
Does this sound like a reasonable course of action?

Buds sliced as though by a knife--katydids will do this. They are hard to spot and catch. With patience, you may spot them. Lacking a butterfly net, I might zap him with an aerosol. They will jump like grasshoppers, and the adults can fly as well.

Thanks, michaelg, for this perfect description of thrip damage: "a bruised and dingy appearance and dry brown edges". Yep, the heartbreak of thrips!

Glad I didn't fall for the systemic tip--yuk. What about nanadoll's suggestion of imidocloprid once in the spring?

And I've been hearing about the new Overture--not sure what's in it, probably something awful, but all I know is it's horribly expensive. At this point, I'd probably pay a lot for a good solution.

Thanks, all, for weighing in--a good buggy thread!

I think imidocloprid WAS the systemic that I used! though it's probably less harmful to the environment if used as nanadoll does, instead of spraying. So, no, I suspect that it might not help at all with thrips (it sure as heck didn't for me, at least!) Fact is, a systemic might not work too well to protect the flowers of a rose, just the leaves,since the flowers are new growth (???).How long have you had the problem? did you use any insecticides in the past? As I said, I'm trying the solution suggested by the Bierkreek nursery, to just not spray ANYTHING against insects,to allow the natural predator population to establish itself.I just think that perhaps the bottom line may well be that in the long run, insecticides don't really work! bart

In my area, my gardens are surrounded by "hay" fields and spring thrips are taken down by the thrip predators that start multiplying exponentially once their food source appears.
All that happens in the hay and the predators fan out.

I don't know if this would work, but for a fall infestation has anyone tried companion planting with grasses? The ornamental ones? That and add some compositae (asters and or cosmos) might give a habitat for predators that they aren't getting in a garden that is all roses.

I wouldn't give up roses without a fight.

That is a good idea,anntn! I'd be more interested in preventing the spring thrips myself...anyone know which are the main thrip predators,and what plants encourage their presence? Compositae in general? bart

In spring, my thrips predators come in from the hay fields which are predominantly grasses with whatever weeds happen to be up at the time.

There are years when the initial thrips surge is so bad, I can have several on my computer screen at night if we leave the windows open.