HMM, rose slugs? It's too early for Japanese beetles.

I never heard of rose slugs. I looked it up and did I read right, that they are sawfly larvae? I did see a black flying insect that was small and narrow, on one of the roses. He didn't seem to be eating anything, but are they laying eggs on the plant?

So, aphids and rose slugs seem to be the problem?

Okay - on the New Dawn leaves.

On the biggest leaf in the field of view, the leaf that has the apical leaflet almost touching the upper left corner of the picture - do you see the uppermost leaflet just below that apical leaflet (the uppermost leaflet being the one that has its leaflet tip maybe 1/2" from the top middle margin of the photo)?

Now - on that uppermost leaflet, do you see the light green straight line that looks like it's sitting astride that leaflet's leaf veins? It's extending straight from one of the damaged white areas of that leaflet.

That's a rose slug.

Yes, they are "sawfly" larvae. Sawflies constitute yet another group of insects in the order "Hymenoptera". The more well known insects in that group are the ants, bees, and wasps. Sawflies are from the more ancient part of that same insect order. To the best of my knowledge all immature sawflies eat plants, but different species focus on different sets of plant hosts. Rose slugs are sawfly larvae that eat rose leaves.

I strongly suspect the rest of your damage (aside from the aphid photos) is caused either by winter moth or cankerworm caterpillars. Both are inchworms, although from different species of moths. Both feed on roses and trees at this time of year. I deal with this damage every year, but some years it's more severe than others. If I'm right, the culprit inchworms are thin, pale green, and only about 3/4" long at maturity. They're little, but they cause a lot of visible damage because they eat at the stem tips. Consequently as those partially eaten young leaves expand and mature the missing eaten areas expand at the same time, leaving very dramatic results.

They're also easy to overlook because they're small and the same color as the young leaves & stems (camouflage and all that).

I usually go around and squish the caterpillars with my fingers, but there are pesticides that will work just as well.

(Actually, by now I suspect you may actually be past the worst of it, and that it will soon not be a problem until next year. This is a very seasonal issue with my roses. Unfortunately it has the biggest impact on the biggest flowering display.)

York Rose, you are a gem! :-) I didn't even see that little insect on the New Dawn! I had my close up glasses on too. [g]

Thripes and sawflies are different, right? I thought I had thripe damage for some reason. But I just looked up a photo of a thripe and I don't see anything like that.

How do these sawflies find your r*oses anyway? Geez! I just planted 4 bareroot plants this spring and they couldn't have come in from the s*oil. Am I doing something wrong to attract them? So the ladybugs will only help out with the a*phids, right?

I am an organic g*ardener, so hand picking would be my preferred method. Or something like the Cornell formula. We had a lot of winter moths in the g*arden this year. I was going to say, that it looks like there is new f*oliage that has not been touched and I wondered if they were stopping. So once you have the sawfly slugs, does that mean the adults are laying eggs somewhere for next year? I suppose I will have to get after them much earlier next year. I will still take a good look and see if I find any and cut off some of the damaged f*oliage and buds.

Thanks so much! I guess it could have been worse. The plants themselves look pretty healthy. I'd rather bugs than disease. I suppose there's still time for that later in the heat, though. [g]

Yes, thrips (no "e") are VERY different from sawflies. Thrips constitute yet another insect order: "Thysanoptera".

Thrips are TINY! At maturity they're usually only about 3-5mm long. They're also quite thin. The ones you most frequently see on your roses are pale gold to pale brown. The ones we encounter here in MA usually cause their worst damage not to the leaves, but to the flowers. Their mouths are basically rasps. To feed they drag their open jaws across the petal surface, and then eat the plant juices that ooze out of the small tear in the petal.

Unfortunately when that gash closes it leaves behind a small brown scar. Over time those feeding scars add up and so the white petal no longer looks pristine, but dingy (like a white t-shirt that's gotten old and is in need of bleaching).

That feeding damage also happens while the flower is developing in the bud, and that can also stunt the flower as well as browning the petal color.

Adult sawflies are small (but not tiny, maybe 1/8"-1/4" long), so they're easily missed. The ones that go after roses are mostly black, and they don't stay in one place for very long at all. They're good fliers, so even if there weren't any sawflies with the roses you bought, once you put them outside and spring was in full swing pregnant adult sawflies would have flown in from somewhere else to lay eggs on your roses. I don't know exactly how they find them, but they certainly do. I assume they can smell the roses, but I don't know for sure.

If you have winter moths around then you will have this problem with your roses every spring. See what you can find out about controlling winter moth organically. I wouldn't be surprised to learn that Bt sprays (made from a bacteria named "Bacillus thuringiensis") control them effectively, but I haven't checked that out so I don't know for sure.

For the larvae of the sawflies, just check in the morning and wipe them off the leaves (check the back side also). With a little patience, you will find that the good bugs will arrive in a week or two and take care of the rest for you. No need to resort to chemicals.

Kate

Except there is yet no established biological control for winter moth. The Commonwealth of Massachusetts is rearing and releasing a predatory fly that only feeds on winter moth, but that program is still in the early stages, and they can only effectively do releases once per year because the fly has to be released such that it coincides with the right spot in the moth's life cycle.

The moth only has one generation per year.

Winter moth is a European insect with no naturally occurring predators in North America.

You can go here to learn more about winter moth in Massachusetts (as well as some other commonly encountered caterpillar tree & shrub pests).

So you can tell by looking at the plant whether you have thrips or not? You didn't see any evidence of them in my photos, yorkrose?

Yes, I have had winter moths for the past four years. It is really a pain, but I keep observing to see how it changes from year to year. This year they were late, but they did show up. They weren't as bad as previous years. One year my two Maples had very visible holes all over the tree. This year I can't see a lot at all. It's even more annoying when they drop down onto plants in the yard. But on the other hand, there are lots of birds that have started camping out for the abundance of food. I see starlings especially like them and are in the trees hunting and pecking. I've seen sparrows eating them and this year I've been amazed to see Orioles hopping around in the trees eating them. So I've held off on using the BT. Right now I think with the few roses I have, hand picking and close observation may keep things manageable. I hope! [g]

Kate, are there bugs that eat the sawfly larvae?

York Rose, thanks for that link. I see they are supposed to feed until mid June. I've already seen a noticeable dropoff in activity.

prairie, yes there are bugs that eat sawfly larvae. Maybe it is a certain type of wasp? I've forgotten which ones they are, but the sawfly larvae problem usually disappears after a couple weeks.

Kate

Thanks Kate, I'm looking forward to that. [g]

Just wanted to update. I spent about an hour this morning going over two roses inch by inch. I had to put on TWO pair of eyeglasses to see the little buggers...lol. They look just like tiny inchworms. Light green with a little deeper green in the middle. The smallest ones and the largest ones look a little different color. One had deep green and maybe a black head on it? No matter, they are all history, I think. I had to pull off quite a few damaged leaves, but mostly on the bottom. Now I can't see anything on them that should be a problem and the new foliage is looking healthy. I will keep my eye on them for the next week to make sure I got them all.

Now to do the same thing to the other roses. [g]

Thanks for all the help! I feel much better knowing that I took care of that and looking forward to some roses!

The damage you displayed in your pictures was chewing damage. Thrips on roses don't cause chewing damage because they don't feed on the roses by chewing. Instead they drag their jaw/mandible (which is a functional rasp) across the surface of young plant tissue (typically young developing flower petals while they're still developing in the bud) and then they eat the juices that ooze out of the wound.

They're far, far, far too small (even as adults) to cause the sort of chewing damage you displayed in your pictures.

That was the chewing damage of caterpillars, not thrips.

Great York Rose, then maybe getting all the caterpillars off will do the trick. Thanks very much for all the help!