european import

Yes, it’s a second post for today. At this time of the year, that can happen. I’ve found that, from the point of view of keeping records, especially when I’m making phenology-related observations, it’s better to keep my observations in separate posts.

Anyhow, I caught this Rose Sawfly (Arge ochropa) in the act of laying eggs on one of the rose bushes in the garden this morning (click on both photos to see larger views). As you can see in the photos – this sawfly makes little slits in the rose stems as it deposits its eggs. Before long, the eggs will hatch and the colorful larvae will begin chomping away on rose leaves. I last photographed one of these sawflies laying eggs in my garden on July 9, 2004. However, I’ve seen them flying around since.

Arge ochropa (also sometimes referred to as Arge ochropus) is an (unwanted) European import that attacks only roses. I found a small article about them in the online newsletter of the Yankee District Rose Society (scroll down for article). I don’t actually know much about these insects other than that they were first found in southern Ontario a few years ago, and have since spread out into other areas of North America. Most of the roses here at the farm are large rugosa bushes, some of which are several feet across, so the damage seems minimal. However, to serious rosarians, these sawflies are considered a major pest. Last week, I found the following message posted on the Pbase gallery under my image of this sawfly:

We live in Watertown, NY which is about 20 miles south of the Canadian border. Last year we were inundated with the stem damage that started as lines and ended as a dark, scabby-like thing, that left the stem with a crook in it. (I’ve gotten so I can spot them across the yard.) Then, we were faced with these sassy, stand-up and fight, type gang of larvae. We killed these all by hand. My family and I have over 80 roses, and we’ve never had these before. I am so glad to finally figure it out. By the way, the rose that was bothered the most was “Carefree Delight”, and next was “Lyda Rose”. The problem is much better this year, so we’ll keep our fingers crossed. Thankyou so much.

I think my own “control tactic” will be to snip off and dispose of any bits of rose canes where I find the characteristic punctures. I won’t go to great lengths to remove them, but when I happen to see a damaged cane — it’s usually the tip of the cane — I’ll pinch it off to try to keep these insects from multiplying. As mentioned, the larvae don’t bother me too much, but it’s probably best not to let them become too plentiful as they are a pest to other gardeners and might well damage some of our native plants.

Phenology-wise, this sawfly sighting is considerably earlier than my July 9th sighting from 2004, so it looks like their active season may last at least several weeks.

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8 Responses to “european import”

  1. sam weisberg Says:


    I sent you an e-mail asking if I could use one of your photos of Japanese beetles for an album my band just finished. Please let me know. You can reach me at Thanks!

  2. bev Says:

    Hi Sam – Just received your email and have emailed you back, so look for a reply- bev

  3. robin andrea Says:

    I’m always amazed how you find insects depositing their eggs. Your timing is really incredible. I’m guessing it’s 1% luck and 99% knowing what to look for. Excellent.

  4. Pamela Says:

    Bev, once again, thanks for the heads up. I had some smaller roses (species and/or variety unknown–one fancy, the other small and rough) stripped by these guys last year. I’ve never seen them or in fact any other serious leaf devastator on the rugosa–just the rose chafers eatign the blossoms.

    I carefully and thoroughly pruned the roses this spring, thinking, hoping that the eggs were laid last year, but now I see that probably wasn’t the case. And these same roses have already had their first leaves sucked dry by something by something, and are just now leafing out again–must go out and see if I can see any sign of new eggs to clip off.

  5. bev Says:

    robin – i think it’s about 50/50 luck and knowing what to look for if you want to find ovipositing insects. I watch for insects that seem to be staying very still and don’t move away when I come near. A lot of times that means they are either laying eggs, or guarding an egg mass, or even their young (some insects do guard their young). Sometimes, the insect is busy eating and won’t leave its food. Either way, it makes for an interesting opportunity to do some insect watching.

    Pamela – Yes, I’ll be that these insects have been doing some damage in your garden. I think they’ve become rather widespread in Ontario. It’s really this time of the year when you could do the odd bit of trimming. I’d be watching for the cuts in the canes – many times it is in the greener parts and the ends, but sometimes in woodier parts of the cane – and I’d snip those off and toss them in the garbage.

  6. Pamela Says:

    Almost too late–I went out to take a look and found two larvae of this sawfly, very small, but on the go. I picked them off and will continue to watch. I couldn’t find anywhere obvious to trim, but found all kinds of other things, including a larva of a different critter–apparently the perpetrator of the skeletonizing, a jumping spider, possible robber fly, rolled leaves, etc., etc. Good thing I don’t grow “show” roses.

  7. Mike Mills Says:

    Bev: photographed this in Thomasburg on the 16th but not id’d.. Thanks…

  8. bev Says:

    Hi Mike – Glad you got the ID and also thanks for posting the info about the sighting. Just keep on doing that all you like as it’s interesting to see dates for sightings in various areas.