Hold on and don't dig them out yet. Knockout roses are very hardy and carefree. Meaning they will grow without our help. Have you fed them yet? The stems have buds that new leaves will come out on. Just be pantient with the bushes and in a few weeks you will have new leaves.

Taking out your knockouts and replacing them with new KO's
will NOT solve you problem.
You will need to figure out what pest is shredding your roses, then figure out what needs done to help the problem.
New KO's will have the same insect problem.

Can you post pictures of the damaged roses? Different critters eat roses in different ways. Posting images of the damage will help us figure out what your likely pest is.

The same exact thing has happened to all 5 of my knockout roses, and a few of my english roses. I have found small green catepillars all over the bottoms of the leaves. They start out really small, and then get big enough to finally see. I just picked off about 50 or so of them and killed them. I purchased my knockouts last year and they were tiny, and eventually grew to about 4 feet in one season, so I am not too worried about them not growing back. I hope you are able to control your insect problem. It's not fun seeing all of those beautiful roses with completely devoured leaves. If you spray, make sure to spray the bottom of the leaves.

lovemyenglishroses, you have sawfly larvae. The OP might, too, but we have no real way of knowing. The best control for sawfly larvae is hand-squishing, even though it can be a painstaking task. if you avoid spraying insecticides the wasps can come in and do their job hunting the larvae. The are very efficient, and fascinating to watch!

I lost a Double Delight to insect damage--not sure what sort of caterpillar looking insect it was--but it was defoliated and never recovered. I was new to rose growing and didn't realize that I needed to do something when I saw those leaves being eaten.

Thanks for all your comments and suggestions! When I was outside planting other flowers yesterday, I encountered a few white larvae. Is that the sawfly larvae Greenhaven mentioned? In any case, I got rid of them. I haven't seen any bugs on our roses, which is why I'm not totally sure what's getting them. As everyone suggested, I'll keep an eye on them, remove the affected leaves, and hope for some new leaf growth soon. Someone mentioned posting pics of my bushes. I don't see a place on this post for doing that, so where do you do it?

Posting pics on the forum. You would have to sign -up on photobucket.com, it's free. You would then upload your pics to photobucket, then copy and paste the HTML code (link) provided for each pic into your posts or threads.

I am having the same problem as waggie450. I have no clue I can see nothing on the leaves. I will try to post a link.

Here is a link that might be useful:

Melissa, your picture suggests damage from sawfly larvae. Don't know what part of the country you are in. In my MD garden by now sawfly larvae is gone, but the damage is here. You can look undersides of leaves. If you see green worms looking like caterpillars, they are sawfly larve. But as I already mentioned, it could be that there are already no larve, it was eaten by benefiicial insects, if you didn't spray any insecticides. The new leaves will grow fast if there is enough water and sun and your soil is reasonable. If you want you can give your roses a litle of fertilizer or compost to speed the growth of new leaves.
Olga

Olga,

Thanks I was doing more research last night on the forums and that is what it looks like. I live Northern KY also. I have finally treated with a different insecticide yesterday because what I used originally did not work.

I personally never use insecticide for sawfly larvae. When I notice first signs of damage in spring, I just use my finger to sqish them. If you catch this problem at early stage, it is very easy to take care of. And beneficial insects will help. If you start spraying insecticides, you kill everything, good and bad. In a long run there is more damage thean benfit. You need good bugs to deal with aphids, thrips, etc. You kill all your natural supporters.
Olga

I've noticed quite a few Jap beetles the last few days. They are eating up my leaves and blooms on my KO roses. I have been knocking them off and trying to kill them.

I also applied Bayer 2-1 rose/flower care granules a couple of weeks back and it states on the lable that it kills adult Japanese Beetles. Well I've seen plenty humping and eating away so not sure if it is working. Have any of you had any luck with this product? I also read that you can spray soap/water on your plants as well?

wmarkw, this product (Bayer 2 in 1) is based on disulfoton, which (to my understanding) the EPA has banned. See the following link which states (according to my interpretation) that Bayer 2 in 1 (432-1286) can not be sold after December 31, 2010.

The EPA information is at: http://www.epa.gov/fedrgstr/EPA-PEST/2009/September/Day-23/p22921.htm

--------------------------------------------------

As to why it can no longer be sold, the following may be "eye-opening" :

"Hazard Rankings
More hazardous than most chemicals in 6 out of 7 ranking systems.
Ranked as one of the most hazardous compounds (worst 10%) to human health."

The above quote taken from:

http://scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=298-04-4

------------------------------------
The summary in the following link:
http://news.agropages.com/News/NewsDetail---1739.htm
may be easier to read than the EPA page.

Here is a link that might be useful: scorecard link for above

At the beginning of the summer I purchased a Terminix All Clear Mister to deal with the mosquitoes in my back yard. It works very well on all flying pests. I bought the All Clear natural concentrate to use in it which is virtually chemical free and harmless to humans, pets and plants. This past weekend I noticed my knockout rose bushes were almost decimated of their leaves. Once I found out they were infested with sawfly larvae, I figured I would try the mister on the plants, since the suggestions posted here seemed very time consuming and not very effective. I placed the mister in close proximity to the rose bushes and gave them 2 five minute misting sessions. When I checked the bushes this morning, dead larvae were everywhere on the ground around the plants, and none appeared to be on the leaves anymore. Hope this helps!

mintboxer,

Thanks, this is interesting. The active ingredient used in the Terminix mister is geraniol, a natural ingredient that occurs in rose oil and is secreted by honeybees.

Thank you, Michael, for checking the ingredients!

I live in NKY and am having the same problem. I noticed the holes in the leaves and so I bought a spray but haven't been home long enough to spray regularly. Now all the petals have fallen off and the leaves are looking like swiss cheese. Not sure if I should spray regularly while I am home this week or leave it alone. I bought Gardensafe fungicide that is supposed to be safe for roses. Will this work?

Andi, You'd need Insect spray for bugs not fungicide. Safer Brand Insect Killer soap, or Bayer's Insect Killer spray should do it.

Using Bayer Insect killer spray for rose slugs (sawfly larvae) is overkill...

Rose Slugs can mainly be found on the underside of rose leaves... You can pick them off your bush or try spraying them off with a hose or do nothing...

Best organic sprays I have found that work are Spinosad and Safers Insecticide soap... (Follow Directions) BUT any insecticide you spray could also kill good insects which is not a good thing...

Gardensafe Fungicide has neem oil in it... Oils can burn rose leaves in warmer temps... Not even sure Neem oil is effective against rose slugs... I would think you would have to coat the insect in the oil in order for it to be effective...

Thanks for your input. We live on the Ohio River, in West Virginia. Lately, we've had daily downpours, some lasting for hours. Now, we find that the leaves of our 5 knockout rose bushes are filled with holes and eaten, in less than 2 days. I was inclined to associate the problem with excess rain, but after reading your comments, I doubt that connection. I'll look more closely for sawfly larva and try your suggestions. Sandra

We're guessing on the sawfly larvae, of course. If you could upload photos of damaged leaves, we could say for sure.
All you have to do, to upload photos, is click on the little "photo" icon shown where you type your post. Then, you can "browse" for a photo in your files.

OR you can go to:
https://www.google.com/search?q=sawfly+larvae+damage&biw=1077&bih=561&tbm=isch&tbo=u&source=univ&sa=X&ei=GVuHVcbyL4-cyATxk63IBQ&ved=0CC4QsAQ
to see what sawfly larvae and their damage looks like.

And, as several have said -- using toxic chemicals for this pest is like killing flies with a sledgehammer. The peripheral damage is worse than the original problem.

Mintboxer, Where did you purchase Terminix All Clear Mister? It's pretty expensive. I don't think HD/Lowe's carry that. It's nice to know it works on sawflies. Thanks for the info. I tried to make 1 gal spray with a mosquito dunk for midge, it didn't work very well, but I did get a few rose buds on one cane out of a whole bush, but that's midge, which is very hard to kill. I know HD & Lowe's have Safer Brand Insect Killer soap for about $6.00/7.00, some of my friends from rose club use that for sawflies and other bugs. I think that's a organic spray, beacuse one of them who uses Safer Brand Insect Killer soap, she eats roses. :-) I use Bayer's Inects Killer this season, because I have midge issue in my rose garden. it does kill a lot of bugs inculding midge, sawflies, bad and good bugs.......I spray it right before dark, so it won't kill any honey bees. This season I also spray Bioneem (about $10 from Amazon), which is also a organic spray for bugs, I'm trying it out for midge issue, it works on sawflies too, but I think that's a strong spray for just sawflies. I spray that at night when the temperture is under 80. I'd say Safer Brand Insect Killer soap is the cheapest if you choose to spray. :-)

Neem oil is what I spray and dont have issues.