The time of arrival and lenght of their presence in high numbers depends on the infestation. In the places where they are really heavy they start in mid June (after the first flush) and go until 4th week of August. You will see some before and after this 8-9 weeks of infestation but only in limited numbers, no serious damage. I the places where the infestation is not so heavy it can be only 3-5 weeks and you can save some blooms by cuttin them early in buds. If there are many, they will eat every bud when it less then pea size, so you can't cut any flowers.
The good thing they don't eat Delphiniums, Honesuckle, Mock Orange, Irisis, Lilacs and Peonies.
In the past they ignored Clematis here, but last 3-4 years they eat them as well.
They like roses (blooms and leaves) and its relatives: apple tree leaves, cherry leaves, plum. They are crazy about raspberry, Linden and grapes. They love Crape Mirtle. Hardy geraniums and bulbs are safe.Daylilies they eat flowers but ignore leaves and anyway all lilies are not their favorite food. Only for fun. Every year they start eating something they didn't touch before.
In the places where JBs are not so bad they only damage flowers, but weretey are in big numbers they will eat leaves and young stems too. Again if it is not so bad some roses (darker and nonfragrant) can be damaged only slightly, but if there is a lot of JBs they will eat any rose, except plastic.

Hopefully somebody from Iowa can tell you do they have JBs or not. And if yes, then how heavy. I really don't know about it.

Rabbits can be a pain and deer, of course too. Rabbits and hares are different animals, but both are bad for roses :(
Olga

In most places JBs only arrive after the first flush and bother mainly the second flush. I don't think there are many in Iowa yet, but the range is expanding. Where it is dry from July through mid-September, the population won't be large except where there is a lot of irrigated turf within a half-mile.

I have never seen roses defoliated by JBs except in photos from the mid-Atlantic area.

In cold areas, desperate rabbits may eat the bark off rose canes under the snow. They may eat enough young shoots in the spring to warrant caging, but not in my garden. Squirrels are just a minor nuisance, maybe eating a few flower buds in the fist flush.

The beetles arrived here on July 5 and are still here. There weren't as many after Sep 1 or so but I can still go out and see them right now. They mostly eat the blooms and a few upper leaves. They defoliated a very small Purple Tiger but it is recovering now. They've never bothered the canes or killed any of the rose bushes. They do eat hibiscus leaves, raspberries, and did a lot of damage to my cherry tree. I actually prefer them on the roses since the roses will recover from losing blooms and leaves, but the cherry is in bad shape.

Rabbits are worse if they decide they like your garden. Last year I lost Ingrid Bergman to them when they ate it to the ground two or three times. Over the winter my dogs killed a rabbit and that kept my yard safe until just last week. A rabbit ate my newly planted Gemini - there is one set of leaves and three canes left. I don't think it will survive the winter. My dogs have been patrolling that area so I hope that keeps the rabbit away. I've also used Liquid Fence this year which helps but it won't stop a hungry rabbit. The only thing that really works is individual chicken wire cages but that's a lot of work when you have a lot of roses. My backyard is fenced, but the rabbits can still find ways in.

Sorry that I can't tell you about Iowa...but....

here in New Hampshire they are still going strong! This is the latest I have ever had to deal with them. They started munching away the first week of July, and here it is almost October and they are hanging on. Grrrrrr!
We haven't had our usual cold weather yet and the summer has been dry, plus our past winter was milder than normal so I'm wondering if those are all contributing factors. I can't believe they are still here!!!

It is extremely frustrating for those of us who already have such short growing seasons. Normally we would have had hard frosts already here in the mountains but except for a couple of nights its been warm. The good news is that a good hard frost should kill the beetles....the bad news is that it also ends my rose season.

My beetles don't care so much for my flowers since they have such a grand smorgasbord of hundreds of roses. I rarely see them on anything else except for the grape leaves. As for my Oriental and Asiatic lilies, they have their own special beetle that destroys them. I don't know if they have them in Iowa. Its a bright red beetle that bores holes through the leaves & flowers and leaves nasty brown deposits behind. I have never seen a Japanese beetle on my daylilies or lilies. My roses don't start blooming here until mid-June, so I have about a 3-week window where I can actually enjoy my roses beetle-free. I hope the beetles don't fancy Iowa as much, for your sake.

Celeste

Celeste, the beetle population depends on last year's weather. If it has been very dry this year, next year should be a bit better.

Thank you so much for sharing your knowledge about Jbs and gardening. I am surprised to hear that they are around for so long!!! I thought it was only about 5-6 weeks. :SIGH:

They do have Jbs in Iowa. I have seen them but nothing like the scary pictures Harry and Olga sometimes have shown !! There was just a few of them on each rose plant. And since I have never been there long enough I do not have any experience of what to expect during a season over there.

The good news seems to be that I can grow a lot of my favorite plants and roses in spite of JBs. And get the informal type of garden I so like. A garden with shrubs and hedges and "Rooms" lots of roses but not only roses and a nice patio. I have something similar to this in mind:

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It is important to begin planting some of the shrubs and small trees like lilacs to begin make the garden more secluded. It also creates a better micro climate and the winters in Iowa are cold, even though it is hotter in the summer and there is more sunlight (same latitude as Rome 2ooo miles south of here !!!).

I know Iowa_Jade/ Foghorn lives very close to Davenport in Iowa and is active in the local rose society (I hope I will be able to meet him and say hello ...when I go there in December). And get the garden going there next summer. (I have had no time for holidays this year due to too much work, so I did not go to the West Coast as I had planned this year, will be next year instead).

Celeste grow so many beautiful roses and she lives in an area that is even colder (incredible). I do know that the roses there will not grow as big as Olga's specimens but I think many roses will grow bigger than here since the summer are warmer/more sunlight. The growing season here are not so long either ... fall is already here but the roses are blooming like winter will never come....

It is going to be different gardening over there and we have to choose were we want live (here or over there or perhaps both? ... having a long distance relationship really is too hard. I miss her every day. And vice versa. Thank God for Im and webcams or our phonebill would have put us into bankruptcy! Life and love happens when we are busy making other plans ... And it seems to be able to live with those JBs and rabbits and still have nice garden with roses.

I came across four Jap Beetles this year and had them confirmed by the Agricultural Extension Agent to be sure. I am totally bummed by that development for sure. I found two alive and two dead. The dead ones were located in a bloom that was open and they had obviously been munching on them and died, probably from the Merit I had sprayed previously to control thrips and cucumber beetles.
I live in St. Joseph, MO--which is located in Northwest Missouri on the Northeast Kansas border and just about 50 miles from the Iowa southern border. If I am getting the beetles now it is more than likely Iowa has a few or is about to get them as well.
John

Just a quick note here to add a few more JB favorite foods to the list:

New summer growth on wisteria (completely consumed)
Hydrangea with the more robust leaves (oak-leaf, climbing, etc.)
Crabapple
Pussy willow

Connie

If they are just starting to appear in Iowa and other states west of the Mississippi, agriculture depts., gardeners, and any homeowner with a lawn should be doing everything in their power to stop them in their tracks. They are controllable when their numbers are smaller. Once they get prolific it's a never-ending battle (they win). I would be spreading milky spore and/or grub killer on turf and making a point of killing every single beetle I saw, and urging my neighbors to do so as well.

Anyways, it doesn't sound like they are too much of a problem in Iowa, and hopefully they won't become one anytime soon. I grow all the other plants you list and don't have a problem with JBs on them at all.

I have a lot of squirrels, but they leave my roses alone. The only times they bother me is when they get into pots of seedlings or new perennials I have waiting to be planted. They like any kind of loose soil, maybe because they think another squirrel buried a nut there. They did make a bit of a mess in my moss garden before it became established (trying to bury nuts under the moss) but this year they have left it alone.

Celestialrose - I still have a few every day here in northern Vermont too. I'm with you - I can't ever remember having them last so long. Granted, it's only 10 or so every day, and they're not destroying anything any more, but still, I'm sick of seeing the lousy blighters.

jont1--I didn't want to hear that. I'm only a short distance on the other side of the Kansas-Missouri border. If you got a couple JBs, that means they are getting too close to me also.

Question: Do JBs eat agricultural crops? What do the farmers do during JB season? Just curious.

Kate

Cupshaped-- 5-6 weeks would be a typical duration.

Kate-- JBs can be a problem on corn and soybeans. Farmers probably use Sevin. I'd guess, many years, Kansas croplands are too dry in late summer for JBs to reproduce much.

Cupshaped,
You also need to read my Rose Rosette E-Book. RRD was used in southern Iowa to try to control wild R. multiflora. Scientists at Iowa State claimed it wasn't a problem for culivated roses. Last year it was a problem in the Reiman Rose Garden and seems to be a problem moving northward within Iowa.
And the soils of Iowa are breathtakingly beautiful.
Ann

Here is a link that might be useful: E-book

Celestial - I too still have JB's. I still have only seen a couple of flowers on Midnight Owl despite the fact that it alsways has 20 or more buds on it - the JB's start mucnching on them as soon as the buds start to develope. I hope it is true that this summer's dry weather means a light infestation next summer - GRRR!

IL zone 5: they begin here July 4th usually. Most of the time they are gone by mid-september. HOWEVER, this year, I found one yesterday... though only one. Longest season ever.

I can't do anything about them because we are surrounded by forest preserve that has wild grapes growing in them. And that is one of their favorite food sources. So we are stuck. I tried the grub control, seemed to help a little. Not a whole lot though.

Spray directly on the beetles with an imidacloprid spray. Doesn't deter them, but it does kill them and reduces their numbers.

Low growing, red and dark colored non scented roses are their last resort. White and yellow scented types are their #1 to go for. Rose de rescht leaves and heritage flowers are their faves in my garden.

I would make sure you plant other flowers with the roses because you won't have any outside for 3 months. Cut and bring in to vases
. The jbeetles also like anything in the rose family: hollyhocks, rose of sharon, etc. Those purple leaf plum trees.

If you have rabbits, etc. I would be careful planting any bulbs. I have a big squirrel problem, and they love my tulips and lily bulbs. You need to plant them with chicken wire covering them and then plant in the ground.
FYI: Daffodils are poisonous to rodents though.

There are effective repellents on the market too. I have used dried blood effectively, although this requires reapplication after rain.

Good luck.

OMG sc_gardener. Heritage and RDR are among my favorite roses!! And I only wants to grow fragrant roses. Which these beetles seems to have a preference for.

I will try to get everyone in the neighborhood to treat their lawns with milky spores. I will probably need to buy bags and bags of that stuff. But If it helps to keep the population down it must be tried. (I found garden supply that sells 50 pounds drum of milky spores. (10 0z should be enough to treat a garden) So 100 gardens in the neighborhood can be treated for $1350 About $13.5 for each garden. That will probably help a bit (But is going to be a hard sell!!!)
and some probably wont allow it or want to pay for it.
Have anyone tried making their neighbors treat their gardens?

Also Harry's beetle traps will probably help a bit too.

Oh Kate and jont1 I have a bit of bad news for you (some friends in Missouri who lives at the Lake of Ozarks had a few too last year ( She said something was eating her roses ) I told her to take the beetles to a garden center in a ziplock bag and they confirmed it was Japanese beetles and sold her Bayer 3 in 1. (as if that should help much).

I will read up on planting bulbs in wire cages that are staked so rabbits and squirrels will not eat them.

Also I had thought about RRD. I will read your ebook Ann. If the roses get infected they need to yanked up and burned Right?

I am the only one in my neighborhood who grows roses, or even gardens seriously, for that matter. We all have lawns (where the JB grubs live). There is no way any of my neighbors would take up the expense of milky spore or even grub killer to treat their lawns (unless they have a lawn service that automatically applies grub killer). Either they don't have plants in their landscape that are bothered by the JBs, or the damage doesn't bother them enough to do anything about it.

CUPSHAPED_ROSES, you should move to California. We don't
have Japanese beetles. I'm curious, what made you decide on Iowa?
I mean it's a nice place, but there are other states that you might like
better.

By the way Niels, those photo's of informal gardens are
so very beautiful. Did you create those gardens? And is
that a blue bridge in the background of the first photo?

Oh, check out the weather, Cupshaped_Roses. Rabbits, hares, beetles, vermin of all kinds, are a constant for gardeners.

But - 28 C...that's something you need to think about, too. Otherwise you won't have any roses for the vermin to eat!

Here is a link that might be useful: National Weather Service charts for Des Moines

Yes Cass I do realize that the weather is very different over there! Cold winters and more windy than here. And it is way more hot May-September than here (90F is a sweltering heatwave here and about as hot as it ever gets). I really need to choose hardy roses (No teas and chinas will survive those winters!!) And HTs will struggle, but are possible in sheltered areas and with winter protection. On the other hand there is so much more sunlight than here (latitude of Davenport, IA is the same as Rome or Cote D Azur in Southern Europe (only the winters are cold inland climate!). I have always wondered why roses get so much bigger in FX Chicago (I see 5-6 feet tall bushy HTs and Floribundas. (Temps are often 12F higher in urban areas, so zone 5 is not just zone 5) But it must be the higher amount of sunlight. If I look at a map and compare latitude to here We get the same amount of sunlight they get 750 miles north of Chicago. (In the Manitoba province of Canada). (We are however blessed with the mild climate because of the Gulfstream and the surrounding sea, but high pressure sends Russian extremely cold temps our way and the temps often drops below -15F.
One thing I always take advantage of is the micro climate when choosing roses. Roses near house walls will suffer less frost damage than roses further away from the house. A patio like that on the picture makes it possible to grow roses that are hardy to zone higher than recommended, because of the heat reflection.
So I know I have to choose roses for zone 4-5 (and 6 in protected sheltered areas.

Devon, It sure would be nice to move to California. But real estate prices there are out of our league! I spotted a beautiful "Prairie Flower" "A Hawkeye Belle...in Iowa ... that is the attraction there....

No I did not "Create" the informal gardens in the pictures. They are just pictures of the style I like and I keep in my collection of gardens that inspire me and the clients I work for. The blue structure in the background of the first picture is a patio deck. It takes time for a garden to mature and most of the gardens I have done lately will take a few years before I will go take pictures of them, since it is important to have pictures of my work. I already have a lot of work maintaining some of the gardens I have done.