The roses themselves will chase them away. "Abstract In warm weather, Macrosiphum rosae (L.) walks off buds of hydrid tea roses during a 'critical period' coinciding with the opening of the sepals. This behaviour could not be related to histologically detectable barriers to feeding, nor to changes in the water content of the tissues or in their composition with respect to total soluble carbohydrate, amino nitrogen or phenolic compounds; major changes in tissue chemistry, effected by spraying the bushes with urea, did not affect the time at which the aphids left the buds. 'Tissue sap' expressed from stems and sepals showed a significant increase in catechin content after rather than during the critical period. Once expressed, however, sap from buds at the critical stage showed a sharp in vitro rise in catechin content over a few hours, up to levels approximating those against which the insects discriminated in choice tests. It is proposed that the insects could well be sensitive to a developing capacity of tissue to accumulate catechin, possibly in response to their feeding activity." Here is a link that might be useful: link for above

I use 'Sluggo' which contains as an active ingredient:iron. For snails and slugs I water the garden heavily, or wait until a heavy rain, and c. 2-3 hours later go through the garden and pick up the snails and slugs that have hidden during the rain and now come out to feed. Then I go snail and slug hunting. I keep a half-gallon paper milk carton by my front porch filled with a saline solution so I always have a quick-kill method and means nearby. I put a plastic bag in it, that I have cut several small holes in the bottom of the bag, this serves as a snail sieve. then I push the bag so it covers the inside of the carton, and tape the handles to the outside of the carton. This way I just pull the bag out and it drains and leaves the dead snails and slugs within for easy disposal. I fill the carton a little less than 3/4ths full with warm water -and add 1 cup of salt. each carton kills c. 30-40 snails and slugs depending on their size. I toss the snails and slugs in it and stir with a stick, hoping they have a quick death. When the carton is full of dead snails and slugs, I pull the bag out and let it drain over the weeds that come up through cracks in my sidewalk and parking lot. salted earth will stop any thing from growing. The ancient Romans salted the fields at Carthage, which inspired me to use this method, instead of Round-up. I only pour the salted water where I want nothing to grow, ever. I keep a carton handy all the time so I never pass by a snail and think "I'll get to you later", because snails breed rapidly and prolifically where I live. They also can move faster than I would think possible, I've set aside four snails, and I went to get the carton and when I came back they had already scampered to the border for asylum, or somewhere. Good luck getting rid of the rose slugs. I killed nearly 500 snails and slugs in March, after they ate my entire Romano bean seedling crop. c. 300 snails and slugs in April, and in May fewer than 200, when I finally dared to plant Romano bean seeds again. I'm gaining on them. Luxrosa

Are these new plants? Or established? If they are established plants I would make an educated guess at giving them a nitrogen boost to help them recover their lost foliage quicker. The rose slugs are indeed grubs...but not caterpillars. As such, applications of something like bT would not be effective. Contact insecticides are supposed to work against them, but they work against the good guys, too, including pollinators. I am battling them, but they are not overwhelming. My plan is to get some good host plants going and introduce biological controls like predatory bugs. Hopefully the garden will find an equilibrium.

Dear Herb Gardener, I'm sorry that the ravenous slugs have hit your Christmas rose and hope that it has bounced back by this time. In my part of the Pacific Northwest (Oregon), we had a very mild winter of 2003-2004, resulting in large populations of slugs, snails, earwigs and aphids to attack our plants. Be sure not to salt your soil when you are salting your slugs and snails, as salt will render your soil infertile. There are two methods of slug and snail control that work well for me. One is catch and release: I handpick the critters when they are out and about after a rain, early in the morning, late in the evening, or at night with a flashlight, as MorZ8 does. I pop them in a plastic bag and keep them in a lidded yogurt container in the refrigerator, and when convenient, I release them in my ex-husband's yard. This can be quite therapeutic. The other method is to use the iron phosphate baits that have been approved for use in the U.S. since 1997. They have been used in Europe for a longer period of time. Iron phosphate interferes with the metabolism of slugs and snails and causes them to stop feeding almost immediately after they consume it. They glide off and die elsewhere. Iron phosphate is an excellent nutrient for the garden, so whatever the mollusks don't eat will benefit your plants. The iron phosphate is packaged in pellets of sweetened bran derivatives, which are safe in your garden. The iron phosphate baits, which are sold in the U.S. as Worry-Free, Sluggo and Escar-Go, are not toxic to birds, insects, fish, pets or other wildlife and are non-toxic to humans, so after reading a lot of research about them, I feel comfortable using them in my garden. I avoid the baits in which the toxic ingredient is metaldehyde, as it is toxic to birds, fish and other critters. If the chemical carbaryl is added to the metaldehyde as it is in some slug bait forumulations, it is also toxic to earthworms and beneficial insects. I used about 3 ounces of Worry-Free so far this year, and am not having a slug/snail problem now. This has also been a bad year for fungus in the Pacific Northwest, because of the rainy spring and the rampant aphids that carry the spores from leaf to leaf and plant to plant. I get pretty good fungus control by washing the plant leaves with a solution of a very small bit of baking soda in water, but I've really had to stay on top of fungus this year. Good luck with both your Christmas rose and your teaching duties. Best, Elizabeth