I know what you mean. I hate those things too.

It's a sawfly larva, so I imagine the flies fly north as the weather warms and lay their infernal eggs...

Here the roses are not weakened by winter or black spot, so they can defoiliate from rose slugs, then refoliate and be fine.

I thought they laid their eggs right on the leaf for the autumn eruption. If not, there really is no reason for me to remove the ugly leaves (except for their ugliness of course...)?? I can live with that.

Susan

I have them, fortunately confined to a few roses growing in pots. Check out the page listed on the link for good information on three different kinds. You can't use Bt -- the larvae are not true caterpillars. According to the information listed there,"they pupate in the soil beneath the roses prior to overwintering" and also another kind "when ready to pupate the larvae bores into the pith of pruned canes". That fits with my experience, that they cycle back and forth within the same plants.

Rosefolly

Here is a link that might be useful: Rose sawfly from Baldo's pages

Looks to me as if I have the one Baldo calls the European Rose Slug. I'll get out the trusty little loupe and look at them more closely. Hopefully that is the only one I have, although he seems to think all three types like it here.

Susan

There is a very easy, organic "cure" for the sawfly larvae. Greenlight Spinosad Spray is an organic biological. It's available as a hose end sprayer application and kills the rose slugs as well as a host of other insects with little effect on beneficials. It can be used on everything in your garden, including edibles and is the lowest toxicity to mammals with a four hour re entry time. I've used it to take care of the Asian Citrus Leafminer as well as rose slugs in clients' gardens for several years. The stuff works and it doesn't stink like BT does. Kim

Here is a link that might be useful: Greenlight Spinosad

Spinosad is toxic to bees, though. If you are going to spray it on your roses, you might want to cut off all the blooms before you do so that you don't accidentally kill any bees. That, or wait until you are between bloom cycles. Bees are in enough trouble already.

As with all pesticides, even organic ones, you want a targeted approach rather than a broadcast application. I'm not saying don't use it; just that you want to use it judiciously. I actually might try it myself on the three roses in pots that have this problem.

Rosefolly

Thanks both of you for the information on the Greenlight Spinosad. I've got enough of an infestation (on many roses in the garden) that handpicking is really just to make me feel better and hardly dents the population which seems to increase every year. I think I will get some and just use it on the ground underneath the roses to minimize the overwintering. That should also limit the impact on bees, dontcha think?

Susan

Me again: What about using Pyrethrin? How does it compare to Spinosad?

Susan

There isn't any way around it, when you spray something to kill something, you're going to kill something else. Pyrethrins aren't any less toxic to bees and is likely more so to other beneficials than Spinosad. For me, the Spinosad makes more sense because I have less slug and far more leaf miner to deal with. And, I just like the idea of it being bacterial than chemical.

According to Oregon State University, pyrethrins are toxic to honey bees. If you were to spray at dusk when bee activity is less, you'll probably affect fewer of them, mostly those who try to spend the night in your rose flowers. They're the culprits for my bee stings. They always happen when deadheading and it's always due to my grabbing the bloom to be cut and awakening the sleeping bee.

Oregon State says:
Pyrethrins are highly toxic to fish and tadpoles. They
affect their skin touch receptors and balance organs
(4).
� Pyrethrins are toxic to beneficial insect (such as
honeybees) and many aquatic invertebrates (4).
� Pyrethrins are low in toxicity to humans, other
mammals, and birds (4).

So, even though they're not as toxic as many others, they do have toxicity to fish, tadpoles and bees, like everything else does. Kim

Here is a link that might be useful: Pyrethrins at Oregon State

So, my thought is to use the pyrethrin (since I have a quart of it here) at the end of the growing season as a soil drench to see if that will keep the population down down for next year. I will only do it under the roses that have been severely affected this year, and as far as I know bees aren't ground huggers, so it should keep the damage to a minimum.

Of course as likely as not I will be too lazy to do it anyway, which will be even less damaging....:-)))))

Susan

Of course as likely as not I will be too lazy to do it anyway, which will be even less damaging

You are not alone...