Japanese beetles took a hit?

veilchen(5b southern Maine)July 20, 2004

Can it be true? Did last winter actually freeze out most of the grubs? Our yard and garden has been infested with them every summer ever since we bought this house. I'm talking millions. One summer, my dh actually used a leaf vac to suck them off the hazelnut and cherry trees (both we chopped down since because of the infestation). Every summer, starting in late June, peaking the whole month of July, and lasting into August, we have JBs galore, esp. on our raspberries, roses, pole beans, hollyhocks, zinnias, and dahlias (in that order).

This year, I can count on one hand the JBs I have found so far. At first I thought they were just late due to the cold winter/spring, but now I'm tentatively starting to think their numbers were decimated last winter. I have spoke to other gardeners in the area who are reporting very reduced numbers or none at all.

I am knocking on wood every day. Is it too early to do a happy dance yet? How are the rest of you faring?

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nancylouise_gw

Veilchen, I can honestly say as of yet I have not seen one JB on any of my roses, HL walking stick, or any other plant or flower in my garden. I am amazed! Even though I lost quite a lot due to last winter's weather, not having JB to fight is an upside from the bad weather. Hope it lasts! NancyLouise

    Bookmark   July 20, 2004 at 8:01AM
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leonessa(Z5 ME)

I have had quite a few, but all in my beetle bags. No where near what were munching away my favorite plants last year though.
Kim

    Bookmark   July 20, 2004 at 9:14AM
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The_Dollmaker

I was thinking the same thing but then I checked my garden log for last year, and the first day I saw them en masse was July 27th. So I'm not home free yet.

Here is a link that might be useful: Kathy's blog from 2003

    Bookmark   July 20, 2004 at 10:10AM
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maine_gardener(Z 5 Me)

I have just started seeing jap beetles this week. They where munching on my roses and my two weeping pussy willow trees. I had to spray with sevin all ready or they would totally eat all the leaves on the two trees.

    Bookmark   July 20, 2004 at 1:55PM
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maineman(z5a ME)

So far I have hand-picked three Japanese Beatles from zinnias, which are their apparent favorite food plant in our garden.

MM

    Bookmark   July 21, 2004 at 1:42AM
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veilchen(5b southern Maine)

I am hoping they are not just extremely late and will be making a strong appearance any day now. I have been inspecting my garden daily and have been amazed at how "beetle-less" it is. Every year, we see the first JBs at the very end of June, first week of July at the latest around here.

If their numbers are reduced, this is the year to really go after them and kill as many as possible, so their numbers don't build up to the previous population again. Even though I normally wouldn't recommend traps, I say use them this year (far enough away from your garden so you don't attract them there).

    Bookmark   July 21, 2004 at 6:32AM
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The_Dollmaker

They always flock to my climbing rose first. Sometimes I stand there looking for several minutes, and when I do, my neighbor shouts "Is it growing?!?!?!" He only grpws stuff you don't have to stare at.

    Bookmark   July 21, 2004 at 7:34AM
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veilchen(5b southern Maine)

Looked again today. It is hot and sunny, and they normally would be out in droves now. I saw one land on my dogwood. That is all. I have not seen a single one on my roses. It's a relief to not have to spray them during beetle season. Now I can say I grow them 100% organically.

    Bookmark   July 21, 2004 at 2:51PM
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luvmyducks(z5 ME)

Either they are very late or dead! I have found one. Normally they are all over my sundrops when they're in bloom, and they've almost gone by without a single one.
Maybe something good DID come out of that winter!!!!

    Bookmark   July 21, 2004 at 3:43PM
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maineman(z5a ME)

LMD,

"Either they are very late or dead!"

I'm thinking just late. I killed two yesterday (on a zinnia) and one today (on an eggplant). I would like to think I seriously dented their local population last year with a ruthless hand-picking program that killed them by the hundreds. But I know matings occurred, and undoubtedly some egg layings. Perhaps our late spring delayed them a bit.

MM

    Bookmark   July 21, 2004 at 8:27PM
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cybertrek(zone 5 Maine)

Boy I sure hope the winter did them in. I dread their arrival and the ensuing battle each year. I saw my first last week but haven't found more than a dozen since. Usually they arrive in numbers beyond counting. Veilchen, I think you may be right about the traps this year, lets kick them while they're down!

    Bookmark   July 21, 2004 at 9:46PM
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veilchen(5b southern Maine)

Maine Man, we always have thousands (literally, and I wouldn't be surprised the actual number reached the millions just on my block). We hand-pick til the cows come home and it has never really made a difference in next year's population. There are just too many.

Most of the grubs underground must have froze to death because the ground froze so deeply with no snow cover. I will no longer be upset about the few plants I lost if it meant alleviating us of our yearly JB problem.

Isn't summer so much more enjoyable without them? No hand-picking twice a day, no spraying. I can actually go outside on a sunny day in July and enjoy the weather without the dumb things landing on me.

I never thought it would happen.

    Bookmark   July 22, 2004 at 7:30AM
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mainerose(4)

We've only seen a few so far, but did put out traps last weekend. Fortunately, my once-blooming roses are just about finished, so I've had a chance to enjoy the show this year without the &^*%$&* beetles!

    Bookmark   July 22, 2004 at 12:47PM
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maineman(z5a ME)

Veilchen,

"Most of the grubs underground must have froze to death because the ground froze so deeply with no snow cover."

I sure hope you are right about that. I have better things to do than shove beetles into a jar of soapy water.

MM

    Bookmark   July 22, 2004 at 10:59PM
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The_Dollmaker

I just spotted the first one, 2 days later than last year, though last year I saw hundreds at this time. It's only 2:30, I went out for a break and saw just the one. I'll go out at sundown with my soapy water and see if there's more by then.

    Bookmark   July 29, 2004 at 2:43PM
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maineman(z5a ME)

I killed three today, off of our eggplants. I also got three yesterday, a couple on the zinnias and one on the squash. So far this is a very light invasion, and no problem. At least, not yet.

MM

    Bookmark   July 30, 2004 at 12:12AM
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veilchen(5b southern Maine)

I keep inspecting and only found one today, snuggled deep in a rose. Squished it. There are so few around here they can't even find mates for themselves. And about half of the few I have found have had the white dot on their thorax (parasitic wasp egg, which also may have had something to do with their demise).

What bliss it is to not have them all over munching and mating. You're right, MM. There are better things to do in the garden than hand-pick beetles several times/day.

But, I got a call yesterday from a person in Waterboro, which is only about 20 miles from here. She said they're all over her echinacea. I am wondering why they froze here, nearer the coast, but are still a problem further inland. It's usually slightly warmer here than there.

    Bookmark   July 30, 2004 at 6:06AM
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maineman(z5a ME)

I killed over a dozen today, including several mated pairs. And now they are attacking pretty much everything: zinnias, eggplants, tomatoes, and squash. I think the battle is joined. So far their numbers haven't justified a killing jar, which I have ready in case I need it.

MM

    Bookmark   July 30, 2004 at 11:57PM
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luvmyducks(z5 ME)

There was a recent news report that the parisitic fly Istocheta has really decimated the population of Japanese beetles this year in southern Maine. My husband saw the report, then went outside to check on our beetles. Most of them have the white dot Veilchen was referring to. So if you're handpicking them, try to leave the ones with the white dots to ensure future generations of the flies. Apparently it only takes a few days to kill the beetles, so they shouldn't do much damage in the meantime. Go flies!

    Bookmark   August 1, 2004 at 7:05PM
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The_Dollmaker

woo hoo! Send em Nawth!

    Bookmark   August 1, 2004 at 8:47PM
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maineman(z5a ME)

Luv,

"So if you're handpicking them, try to leave the ones with the white dots to ensure future generations of the flies. Apparently it only takes a few days to kill the beetles, so they shouldn't do much damage in the meantime. Go flies!"

I'll look for the white dots. But the problem with letting the infected beetle have free reign for a few days is the beetle may mate and lay eggs of its own during that time.

MM

    Bookmark   August 1, 2004 at 10:59PM
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veilchen(5b southern Maine)

I think it was a combination of the parastic wasp and the deep cold. We started seeing evidence of the parasitic wasp 3 years ago. The past two years there were many beetles with the white dot. But for their numbers to go from the thousands down to about 50 (so far) is remarkable.

I have a JB with a white dot in captivity in a jar, feeding him rugosa leaves. I was curious to see what exactly happens when the white dot hatches. It's been going on 5 days now and the beetle is still alive, white dot intact.

    Bookmark   August 2, 2004 at 8:03AM
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maineman(z5a ME)

Veilchen,

"I have a JB with a white dot in captivity in a jar, feeding him rugosa leaves. I was curious to see what exactly happens when the white dot hatches. It's been going on 5 days now and the beetle is still alive, white dot intact."

If something interesting happens, let us know. Even if it is gross. Especially if it is gross (grin).

MM

    Bookmark   August 2, 2004 at 10:25AM
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maineman(z5a ME)

I first noticed on of the white dots on a JB today and spared it and another one as well. Or maybe it was the same one that just moved to a different place. It might not be politically correct, but all Japanese Beetles look alike to me. (grin)

MM

    Bookmark   August 3, 2004 at 12:34AM
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maineman(z5a ME)

That should have read:

I first noticed one of the white dots...

MM

    Bookmark   August 3, 2004 at 12:37AM
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veilchen(5b southern Maine)

Well, I just checked the beetle and he appears dead, white dot still on him. Don't know if the wasp larva hatched and did him in, but is too small for me to see, or if I starved the beetle by forgetting to give him fresh leaves yesterday. So much for my scientific experiment.

    Bookmark   August 3, 2004 at 6:36AM
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luvmyducks(z5 ME)

MM, I seriously doubt if a beetle infected with a parasitoid that is eating it from the inside out will feel much like mating and laying eggs. I mean, have you seen Alien? ;-)
But seriously, I recently spoke with an IPM specialist at the UMCE Pest Management Office. He recommends that infected beetles be left alone. He also told me that they are attributing the decline in beetles this year to a combination of the cold winter, lack of snow cover, and high levels of the parasitoids last year. So Veilchen, I think you hit it right on the nose.

    Bookmark   August 3, 2004 at 2:11PM
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maineman(z5a ME)

Luv,

"I seriously doubt if a beetle infected with a parasitoid that is eating it from the inside out will feel much like mating and laying eggs. I mean, have you seen Alien? ;-) "

I have been watching one of the white dot JBs for the last couple of days. He (or she) hangs out on the same eggplant and doesn't seem to be eating much, if anything. And he acts quite docile. No tendency to fly. So I now have no misgivings about leaving the Japanese Beetles with the white dot on their thorax completely alone.

MM

    Bookmark   August 4, 2004 at 3:10AM
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veilchen(5b southern Maine)

It is difficult to leave the JBs with the white dots alone when they are mating. As in, what if they lay eggs before they die? I have seen some very vigorous JBs with white dots eating and mating.

I think how the process goes is: the white dot is the egg, and is just attached to the beetle for a certain period of time until it hatches (one week?). Once the egg hatches into the wasp larva is when it bores into the beetle and kills/eats it. Then the wasp larva goes off (where?) and morphs into the parasitic wasp, to lay more eggs on JBs. Or maybe completes its life cycle on the JB body before going off to lay more eggs.

    Bookmark   August 4, 2004 at 6:50AM
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luvmyducks(z5 ME)

I got this off the USDA's APHIS website:

"Istocheta aldrichi--This solitary fly is an internal parasite of the adult Japanese beetle. The female flies are capable of depositing up to 100 eggs during a period of about 2 weeks. The eggs are usually laid on the thorax of the female beetles. Upon hatching, the maggot bores directly into the beetle's body cavity, killing the beetle.
Because it does not take this fly long to kill the beetle, I. aldrichi can suppress Japanese beetle populations before beetles can reproduce."

Great topic, everyone!!! I'd never even heard of this fly until this year.

    Bookmark   August 4, 2004 at 1:21PM
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maineman(z5a ME)

I killed several more JBs today, and spared two beetles with two white dots each, as well as three with one dot. All of them were perky, but I expect with time that will change. I was beginning to think that the white dot beetles were rare, but apparently they are fairly plentiful.

MM

    Bookmark   August 5, 2004 at 12:10AM
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