Rose Pest Identification

thejackllMay 5, 2012

Hi - I think leaf rollers have infested one of my roses, but none of the pictures I find look quite like what are on my plant.

These are larvae / caterpillers.

-stretched full length they are 1/2 to 3/4 inch long

-color is light green with a reddish dorsal stripe

-they perch with their waste extruding end on the stem below a rose bud, and their consuming end just above the base of the bud

-they chew a hole in the bud, sometimes multiple holes

-a black drop of waste oozes out the hind end

-many of them have formed webbing around the leaves next to the bud - it does not quite form a cocoon, the worms are visible through the webbing, and little black crumbs of what I presume is wast accumulates on the outside

I only noticed them on the buds today - and I've been watching this bush for the last week fairly closely waiting for it to bloom. I did not catch them hatching from anywhere, so do not know if they came from the soil or the canes or the leaves.

I would like to identify them so I can use a preventative spray of some kind. I got rid of all I could see by cutting off the buds and sealing all of them up in plastic. These worms are only on this rose bush, I have about 6 total that are leafed/budded out to the same extent but see no worms on those.

Thanks in advance.

Jackie

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michaelg(7a NC Mts)

All pests of this sort begin with eggs laid by a winged adult on the foliage or stems during the present season.

Insecticides should not be regarded as preventative. You should apply them only when pests are present and doing damage. In this case, with only one rose affected, I would simply pick them off and squish them. They will probably not return this season after you wipe out this generation. You can prevent serious damage if you scout for them every day for a while.

They are either sawfly larvae or moth larvae, probably sawfly from the behavior you describe. Either can be killed with the relatively safe insecticide spinosad, sold under a variety of labels that will turn up in a web search. You may need to get it by mail. However, any insecticide will harm beneficial insects as well as pests.

Thanks for your careful observation and description, as opposed to the "Help!!! Something's eating my roses!!!" posts we sometimes get.

    Bookmark   May 5, 2012 at 10:49AM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

I usually just squish them. They don't usually get out of hand here. Maybe a beneficial something eats them? And I have a bunch of birds.

They have gotten out of hand, though, so I very, very rarely use some spinosad and pick any open blooms off first, so the bees won't get close to the bush (hopefully). I certainly don't use it unless my buds are getting eaten very badly (which may be a different kind of caterpillar in any case; I see lots of things on my roses, lol). The spinosad works, but please consider the bees if you choose to spray your buds.

    Bookmark   May 6, 2012 at 2:16AM
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