I pick rose slugs off the leaves and toss them into the grass. I doubt if they ever make it back to the rose bush.

If you don't spray insecticides, the "good bugs" will show up and finish off the rose slugs.

If I have a rose slug problem (some years I do, others not), it only lasts for a couple weeks, what with me tossing slugs and then predaters arriving to eat them.

I am not aware of slugs "dropping." They hide on the underside of the leaf and keep on chomping until the gardener and the predator intervene (as far as I know).

Kate

It's just a question I've had on my mind and researching it has lead no where. One article says one thing and other articles say something else. lol.

Here's an answer that google turned up (in the last paragraph).

Here is a link that might be useful: Somebody's explanation

>It's just a question I've had on my mind and researching it has lead no where

Hi Jim,

I don't know the answers to your specific questions. But we've had a terrible rose slug problem here too and I've found a few bits of information you might want to know about (if you haven't already found them):

There are multiple varieties of sawflies that can affect roses, and they don't all emerge in the spring at the same time. Damage from one or more varieties can go on a long, long time. One particular variety can pupate multiple times in one year, and each time a new sawfly pupa climbs the rose it can molt several times in growing and eating there. I assume (from having seen pictures of adult sawflies as flying insects) that when it's finished growing and eating the rose while it does that, an adult sawfly simply flies away to lay its eggs (probably in the soil).

There is a beneficial nematode that can take care of sawflies in the soil but it's apparently not available in the United States. (Phasmarhabditis hermaphrodita.)

The one thing I've found that is easy to use against sawflies is something with the active ingredient of iron phosphate. I can't swear that it works--just recently started with it--but some people seem to think it does. You sprinkle it at the base of the rose where it is likely to waylay forever the slug on its intended journey up the rose.

Spinosad might also be effective (not tried that one yet) as a spray on active slugs on the plants.

My organic gardener's handbook suggests not handling the slugs barehanded, because they say it can be severely irritating to your skin. That might apply only to some varieties or to all varieties only during certain stages of growth? (I didn't notice irritation on the kind of sawflies that emerge early in the spring here.)

Best wishes,
Mary

Here is a link that might be useful: Pesticideinfo for Escar-Go! and other iron phosphate pesticides for slugs

Hmmm....a "slug" and a "rose slug" are two different things. One is an invertebrate and one is a wasp-like insect larva.

I've used iron phosphate products for slugs and snails and it works, but I don't think it's effective for the sawfly larvae.

I have knocked off sawfly larvae and seen them crawling back up the rose, the little buggers, so I squash them. I have the best results if I kill as many of the first generation as possible--as soon as I see the first damage--this cuts down the population significantly.

There are also these tiny little birds that fly in groups through my garden picking the things off. I love those little birds. Also reportedly hummingbirds will pick them off, too.

Bushtits.
Tee hee.
Renee

HoovB, so they can climb back on to the rose bush.
I'm more or less just trying to learn more about them and there behavior.

Other question: Do rose slugs only feed from the underside of the leaf??? Has anyone every spotted them on the top side of leaves or on the canes???
Reason i'm asking is that last season I had hundreds of rose slug looking critters on our roses in Mid to late August. On the under-side, top - side, and canes. They could be seen day or night on the bush. Feeding seemed to be done mostly at night though. I even found an article with the exact picture of what I had and they had it labled as a rose slug.

http://www.finegardening.com/pages/g00171.asp

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The below pic you can see the damage at the top. If you look on the right side not quite half way down you can see the critter curled on the top side of the leaf.
{{gwi:277242}}

Jim, there are at least 4 types of sawflies that eat rose leaves, others that bore in stems. The most common kind when young makes white windows in the leaf and later skeletonizes. These feed only on the underside of the leaf, and they apparently have more than one generation per year. Yours are something else, and I don't know whether it is a sawfly (probably) or a caterpillar.

There is some confusion about life-cycles in this thread. It is winged adult-> egg on leaf-> larva on leaf-> pupa in ground-> adult. Larvae do all the damage, and I doubt they would leave the foliage before their job is finished (either they mature or there is nothing left to eat).

>Other question: Do rose slugs only feed from the underside of the leaf??? Has anyone every spotted them on the top side of leaves or on the canes???

Jim, my memory is incomplete. I might have seen some on the tops of leaves, but if so, that's not the most common place to find them. For sure I've seen a zillion of them on the canes, as well as the undersides of leaves. I've also seen multiple times when canes were chewed all the way around, sometimes leaving just a thin thread holding the upper part of the cane still attached but hanging down totally upside down. And I've often seen long, often not so shallow, chewing cuts into the cane, going down or up the cane from somewhere in midcane. Usually, but not always, this results in the cane turning totally black throughout that cane area, necessitating that that dead cane be cut off and sealed. And if I didn't seal the ends of any sizable cut cane, that cane would become black fairly quickly and have to be cut again and sealed. Lots and lots of that happening here, starting in April and going on well into the fall.

Until the start of Rose Rosette Disease here, this was by far the #1 problem for our roses--with blackspot, cercospora or anything else not even coming close. My theory is that because our yard has lots of woods and also some pretty low damp areas (especially last year when we had an unusual amount of steady rain throughout the summer instead of drought) it has or had conditions especially liked by sawflies.

>I even found an article with the exact picture...

I don't think I remember ours being curled around, though some might have done that and I was just focused on the straight kind. Using photographs, I've seen many, many straight ones climbing canes and on stems. They are hard to notice with the naked eye, but enlarging pictures on the computer screen works wonders. I don't have pictures of the undersides of leaves, but for those I turned over, I could notice them with the naked eye better... and there were a lot of those there too.

==
>I've used iron phosphate products for slugs and snails and it works, but I don't think it's effective for the sawfly larvae.

Thanks for your information, Hoovb. Oh, well! We already do have the product, so we'll give it a try anyway, hoping that our varieties are a bit different than yours. Grasping at straws here, I know...

The roses I started trying the product out with a couple of weeks ago have already succumbed to RRD, though, so I've no idea thus far on whether there's any chance that it might work here. Your post inspired me to actually read the label (novel idea!) and I did not see any of the specific types of slugs mentioned there that I could find in one of my books as some of the sawfly slug varieties that can affect roses, so your experience might well predict ours too. On the optimistic side, though, it does say that those particular varieties listed aren't the only kinds of slugs it will work with, and mentions also that it's effective for slugs on blueberries and apple trees (plants with some relationship to roses, I think). Anyway, we'll see... assuming that by the time RRD is finished with us here we have some roses left to try the product on.

Oh, I did read one other interesting thing: if you don't want to pick each and every one off by hand--no chance!--one of my books says that a strong spray with the hose will work. I don't know what percentage will have the strength to climb back up, but the spray coming from the side will at least put them at some distance away from the cane (and for all our new roses in the pots, they'd have to climb the pots too). I've been mainly doing that for aphids, but it will certainly be a bonus if it helps with rose sawflies too!

Best wishes,
Mary

Thanks for all your input Mary! Much appreciated!

Jim,

I've just been squeezing rose slugs this week. They are my #1 pest. Mine always stay underneath the leaf. I have never, in 8-10 years seen one on top. They must travel to new leaves after the sun has gone down.

The new babies are too small to be seen and can only feed on one layer (not through the leaf) which means by the time you see damage they are large and easily 2 dozen visable ones on a bush. They have never done damage except to skeletize foliage.

If your potted rose became host to my rose slugs, those lovely looking leaves would be eaten between the veins in about a week. I gave up the fight last year and used a combination fertilizer-pest systemic on the potted roses. Within 4 days when I lifted the leaves, there were dried up blackened bodies.

Whoever named them slugs was spot on. They move slowly (not like a caterpillar which can twist quickly) and the bodies are soft looking. Mine are totally green with no discernable head or rear.

Mine also have several generations per year. Your caterpillar looks like those I pick off the petunias.

iris-gal, My pic above was taken at the beginning of the damage. They shredded most of that plants leaves, but, by October all leaves were replaced and you couldn't even tell it had any damage. I'll see if I can locate those pics.

Mine look exactly like this pic on this website article, I mean they could be twins. lol. But, is the article correct in labeling it a rose slug? I do not know?
If I have the problem this year, I'll take better close-up pics of the critter and i'll place some in a glass/plastic jar and try to find a local source who can positively ID them.
I just want to learn more about insects that damage roses.
And how to identify damage, etc.

http://www.finegardening.com/pages/g00171.asp

Can anyone explain the body style differences between Sawfly Larvea (rose slugs) VS. caterpillars?

Mary and others-- again, there are at least 4 different kinds of sawfly larvae that eat leaves. They are are called rose slugs, but they are different.

Jim, the two kinds of worms (moth/butterfly larvae and sawfly larvae) are distinguished by counting the legs. All have 3 pairs of true legs near the head and then some "prolegs" further back. Sawflies have more than 5 pairs of prolegs, caterpillars have 5 or less.