Black Japanese Beetles

lainey2(7a)June 29, 2013

This year my Japanese Beetles are black, rather than iridescent, and they hide under the flower or deep in the folds of the petals. Is this a different variety of beetle or have they learned to survive by hiding through natural selection?

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This is a different variety of beetle. Most of the beetles I've seen so far have been of the (tan) oriental variety. Only one JB so far...

    Bookmark   June 29, 2013 at 3:17AM
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nickl(Z7a NJ)

There's only one insect that is commonly called the "Japanese beetle" (Popillia japonica) and it is never black.

There are numerous beetles that can feed on roses from time-to-time. However, many of these are of only minor concern

As applied to insect pests, it is extremely important to accurately identify the insect so you can, firstly, determine if control is warranted at all, and then, secondly, correctly apply the proper control.

    Bookmark   June 29, 2013 at 10:17AM
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They look like Japanese Beetles, walk like Japanese Beetles, and eat like Japanese Beetles, but they are black. They are voracious eaters of roses.

    Bookmark   June 29, 2013 at 9:57PM
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rosetom(7 Atl)

I've seen them on my roses, too. According to some university entomology departments, they seem to outnumber the "legitimate" JB's this year so far. Strigoderma arbicola is the name of the "false Japanese Beetle" whose habits of eating rose blossoms are identical. They're dark-brown to black.

    Bookmark   June 29, 2013 at 10:58PM
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ratdogheads(5b NH)

What I have known all my life as a Japanese Beetle is copper colored. I have something here that is the same size and shape, however they're tan with some black striping. They surely eat and act just like a JB. Does anyone else have them or know what they are? I've lived in NH 5 years and I've never seen the copper colored ones on my roses.

    Bookmark   June 30, 2013 at 6:42AM
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rosetom(7 Atl)

Technically speaking, the wings are copper, while the head and thorax is green. However - I can't find this documented anywhere yet - but I wonder if the coloration is an optical effect. A regular JB can appear black when in-between the petals of a bloom. It may be that the parts are truly black and simply reflect a certain color under the right conditions.

The Indigo Bunting has feathers that are truly black, but the bird is blue. Apparently, this is the truth for all blue birds according to Cornell University:

Anyway - my post about the "false Japanese beetle" is also true.

    Bookmark   June 30, 2013 at 10:08AM
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nickl(Z7a NJ)

"False Japanese Beetle" is one common name for Strigoderma arbicola, although that name is not much used in this part of the country. . Around here, they are usually called "Sand Chafers". They come in a black version and a red one- the photo is of the black version.

They aren't uncommon in this area, but they are much more of a problem to farm crops than they are to roses.. Although they will occasionally migrate in from the fields to the roses and to other plants, their damage is localized and not significant. So if you saw one on roses here, I'd be suggesting you hand pick it - or just do nothing.

It may be a more significant rose pest in other parts of the country, of course.

That's why it's important to accurately identify the insects you may see on your roses..

    Bookmark   June 30, 2013 at 11:34AM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

I have seen the red ones (Strigoderma arboricola) in my gardens, but thankfully they have not bred here in my garden/area like the JB population does. Those get inside fairly often if I'm thinking of the right 'bug'.

JBs wouldn't be so awful if their numbers were just lower, imho. I have a few kinds of rose-eating beetles in my gardens, but none seem to do the kind of damage so many JBs make. I'm sure they could in enough numbers! The grasshoppers also give the JBs a run for their money some years here (this one).

    Bookmark   June 30, 2013 at 6:01PM
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You are right rosetom They are black and as destructive to roses as the more common Japanese Beetle.

    Bookmark   July 1, 2013 at 10:23PM
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sandandsun(9a FL)

"Only one generation is completed each year."

I hope North Carolina State Univ. is correct about this.
See link below.

It would mean that killing them could be very effective.

My thanks to rosetom for identifying them as Strigoderma arbicola.

One thing NCSU didn't get correct - their range; it definitely extends to Florida!!!!

Here is a link that might be useful: Spring Rose Beetle

This post was edited by sandandsun on Mon, Mar 31, 14 at 20:42

    Bookmark   March 31, 2014 at 8:40PM
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What you have is the oriental beetle which can be black. They were much worse in CT than JB's.

Here is a link that might be useful: Oriental beetle

    Bookmark   April 1, 2014 at 1:02PM
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sandandsun(9a FL)

You are entitled to your opinion of course, henryinct, but I'm convinced that I have the domestic type as identified by rosetom and referenced in my previous link.

On that linked webpage, the beetle is identified in the illustration at the top right as commonly being called sweet potato flea beetle.

That nickname makes it overwhelmingly likely since folks in Florida who can grow plastic flowers well also have success with sweet potatoes until pests and pestilence find the vines.

I'm convinced.

    Bookmark   April 1, 2014 at 9:46PM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

Well, I hope you can control them with a milky spore or whatever is used on them! :) The few I see can do a lot of damage, so if they brought all their friends, that would be a huge problem.

Judging by the insane amount of mole tunnels I have in my yard (and the neighbors') this fall and winter, I should have many fewer of all those voracious beetles! I hope moles can eat a ton, lol :) Maybe I won't have to cut off all my roses this summer, which had become my strategy, like waving a white flag.

    Bookmark   April 2, 2014 at 4:36AM
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sandandsun(9a FL)

A past or current curator of the Biltmore Estate Rose Garden said - I think it was on rose radio, that he would go about the rose garden very early in the morning with a bucket. If I remember correctly, he said he used kerosene instead of soapy water. In the early morning walk about, the beetles were knocked off into the bucket and were a problem no more.

I mention this because I don't grow plastic flowers or sweet potato vines; it is unlikely that they are reproducing in my yard.

I, for one, will not sacrifice my flowers to predators.

You may of course do as you please.

    Bookmark   April 2, 2014 at 2:07PM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

I tried, but about half of them fly away as I do it. But when there are multiple dozens of JBs on side-by side blooms, it's hard to get them all to fall where you like, lol! For the other types of beetles it's no problem comparatively in my yard, so I do hand treat those.

    Bookmark   April 3, 2014 at 1:39AM
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Back in CT we had huge numbers of oriental beetles which were often all black but I think there were blackish larger beetles which must have been the spring rose beetle. I'm sure they were outnumbered 100-1 by oriental beetles as were Japanese beetles so I didn't notice them that much. From all the descriptions I have seen however the spring rose beetle has color variation even when black so I still wouldn't be sure about the identification. The key would seem to be the size and look for a little greenish on the head and slight color differentiation resembling that of the JB.

Here is a link that might be useful: spring rose beetle

    Bookmark   April 3, 2014 at 11:21AM
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I just have to say that it was funny to see a JB with a large pin piercing it body! They are the worst bugs ever!

    Bookmark   April 3, 2014 at 3:47PM
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