Sawfly Larvae (Rose Slugs), A Rose Foliage Pest

Sawfly larvae

Annoying little beasties, though not fatal to the rose, they merely ruin a lot of the foliage by chewing it full of holes, sometimes to the point of eating it all.   Various genus and species within the order Hymenoptera.  (This is science-talk for "There are a lot of different kinds.")  They are commonly called "Rose Slugs".   They are not slugs, however, but the larval form of Sawflies, a wasp-like flying insect. 

They are most often host-specific, meaning they go after one type of plant--there is one kind for elms, one for pecans, others for oaks, ash, many other plants, and unfortunately, at least a couple for roses.  One type has only one generation per year:  you get a few weeks of damage, then they vanish for another year. 

This garden seems to have a more annoying type, which produces multiple generations per year, and therefore a lot more damage.  I have best luck being alert for initial damage, and rubbing the backs of the affected leaves to kill the tiny, hard-to-see larvae.  If I can kill enough of the first generation, damage is significantly reduced.  In my less experienced gardening days, the thought of squishing little worms was repugnant, but now that I'm a hardened veteran, I squish away until my fingers are green.  What we do for our roses, eh? 

Sawfly larvae

Sawfly larvae

Note I mentioned nothing at all about insecticide.  I'm not fanatically "organic":  in a dire situation I'll break out an insecticide.  However, I have yet to face a dire situation with roses in this garden.  Even a lot of Rose Slug damage won't kill the plant, and small birds, ladybug larvae, and lacewing larvae do appear to eat the pests.  Soon enough the rose grows new foliage that covers the damaged leaves.   In weighing the negatives of insecticide vs. the negatives of Rose Slug damage, the insecticide negatives far outweigh the Rose Slug negatives.  Hence, green gooey fingers.  But they wash off. 

Rosa 'English Garden'

Comments

  1. Rose slugs are such a pain! I do see hummingbirds eating them in the spring though. I find I get them mostly on roses that are planted close to the house or some other structure that keeps them from being visited as much by the birds and beneficials. I have also noted that some roses with thicker leaves rarely get them.

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  2. I am not sure this is right place to ask my question, but as it is a bug issue I thought I'd start here. I notice a tiny black infestation on the blossoms and new growth of my succulents (including those that have a rose like appearance so I hope I am blending here ok.) What are they and how to treat? I usually cut off the infected parts. Ok to do?

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    Replies
    1. Tiny little black bugs? Those are particularly persistant black aphids, tough to get rid of. Spray with a 50/50 mix of isopropyl alcohol and water. You have to spray daily (or even twice a day is better) for a while and even then they are tough to eliminate.

      Is that what you mean, or are you talking spots or marks on the foliage? If spots, can you post a photo on your blog?

      Hope that helps.

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