Have you given the natural predators a chance? What is a horrendous problem? To me part of the fun is watching the natural balance work. We have some warm weather coming and the garden will be filled with Ladybugs dining on aphids. And BTW I believe that systemic insecticide gets in the nectar and pollen and kills the bees and gets into the honey they make. Go out and kill the slugs with your fingers. You will be doing the world and yourself a favor.

I know that you are asking about the "big guns"..but my mother always put pie plates down at night and filled them with about a half inch of beer, then every morning dump the slugs, and there were tons of them!! Strange, but true..slugs must like a nip now and then...Donna

Yes, henry, I have watched the wasps working the roses, and have been hand-picking, and picking, and picking, and picking. A horrendous problem means that I have whole shrubs being completely defoliated. Ironically I have some that are not touched at all.

Donna, I appreciate your input, and it's great advice! But these are not true slugs, but sawfly larvae. They aren't really slugs, nor are they caterpillars.

If systemics get into the pollen and nectar then that is out of the question. *sigh* I guess I'll consider like a Cornell formula spray, or just try to stay up on handpicking. I am not optimistic there.

You're braver than I am..because if I had to touch them, I don't know if my roses would make it!!
I am sorry you are going through this..maybe someone with sawfly larvae experience will read this and post a solution.
this is a gw post about them on another forum...seems murphy's oil soap might work..

http://forums.gardenweb.com/forums/load/cangard/msg0616333613557.html
good luck..donna

Honestly, squishing 'em seems to be the most effective thing I've ever found.
In fact, when rose slugs show up, they must send out some sort of radar, because they are usually followed by a big flock of bushtits.
And when the bushtits leave, they don't leave any rose slugs behind, and they take care of any aphids while they're at it.

Jeri

I have never seen any of those, but I would welcome them with open arms! I had my Lavender Lassie covered in aphids earlier this week, but she seemed to be the only one. Ironically, it was another hybrid musk, Darlow's Enigma, that struggled with aphids last year...

I have been both squishing and flicking the rose slugs...they don't climb back on, right? I thought I remembered that from last year. Something I learned in Perennials class this past semester was that Mugo Pines are a main host of sawflies. Luckily I don't have any of those, or I would have yanked them.

they don't climb back on, right?

*** I squish every one I find.
Those little devils aren't going NOWHERE.

Jeri

Insecticidal soap such as Safer's ought to work. It takes around 24 hours to kill. One notch up from that would be spinosad, which would persist for a while as more eggs hatch.

Spinosad has a good environmental profile and won't encourage spider mites, but don't spray it into open flowers. It is sold as Ferti-lome Borer, Bagworm etc., and as Monterey Insect Spray. I don't know whether it would affect wasps feeding on the rose slugs, but it might.

Thanks for all the input! I was picking up some RoseTone and decided to purchase a bottle of insecticidal soap. I know I risk some leaf burn, but some bushes are nearly completely defoliated. I treated only the worst bushes, and will continue to handpick. I think it is important to try to smother new eggs, too. So maddening.....when these are done the JB's will be here. It's almost enough to make me give up on roses. Of course, when that first bloom pops open I will be so grateful and change my mind! :o)

I've been picking them too. A lot. I've paid my son a penny a slug as well. My reasoning is to squish them rather than just knock them off on the theory that if they have eaten enough to be mature sufficently, they will continue the life cycle and reproduce again. Sorry little buggers, you're history.

The only thing other than hand-picking that I have found to work on sawfly larvae is the Bayer systemic. But its a pretty nasty chemical, so you might not want to use it. Of course, on a really huge climber/rambler, hand-picking is, to say the least, difficult!

If you start early with squishing, it's much easier to maintain control because there won't be so many chewed leaves to inspect. If you don't let any survive to pupate, there will be fewer next year. There is only one generation, so you only have to police in the early season.

Bummer, cuz there are gobs more this year than least year, and last year I stayed right on top of them.

So the BT I sprayed this morning does not work on these little worms? My Clair Matin and new Spice plant are infested and I cannot get to all of it. It's just too difficult to find them all. This makes me unhappy.

So the BT I sprayed this morning does not work on these little worms?

*** No. But it is very effective on butterfly larvae.
:-(

I honestly tried various things when a rose brought in from a nursery came loaded with these pests.

Nothing worked.
I ended up sitting on my rear on the hillside for a couple of hours squishing them.
That worked.
It was a pain in the rear, but it worked.

Neem Oil might work (we didn't have Neem oil then) but keep in mind that it is death on bees and aquatic critters, and could cause complete loss of foliage if you get hot weather soon after using it. I have it, but use it rarely.
With MY luck, I'd use it, and the next day the thermometer would hit 90.

Jeri

I had the same problem this year and they seemed to come from the new, potted plants. The established plants were eaten, but not as badly by any means. Except for Reine Victoria, eaten to shreds? I persist in thinking that all foliage tastes different (have not tried any myself) but others make fun of me.

For example, chinas are evidently delish to rabbits.

I persist in thinking that all foliage tastes different (have not tried any myself) but others make fun of me.

*** For why do they make fun?
The petals of various roses taste different. And the foliage of many roses offers unique smells. So why would some foliage not taste different?

For example, chinas are evidently delish to rabbits.

*** !Que lastima!

Jeri

Oh, I believe too, that even bugs have their favorites. I have a plant eaten to the nubs right next to one that is almost untouched. They know whats good...unfortunately for us. :o(