What I remember about that natural predator is that it thrives in the JB's native land of Japan and East Asia, but not here, for whatever reason. :( There JBs are not the problem they are here, because of that.

There are many tiny wasps, smaller than pin-heads, that are pretators of bugs and insects. "Red in tooth and claw" extends to the insect kingdom

Robber Flies and Prayng Mantises are reported to eat Jap beetles, but not in significant enough numbers.

I observed a (large) Praying Mantis grab a Japanese Beetle and then immediately release it.

I say hot soapy water is JB's only natural predator.

I didn't realize that the wasps don't exist here...that's surely a shame! I was "hoping"!!! Thank you for that information. I will go back and check out that site...I was in a hurry at the time.

I haven't seen any pray mans lately. Course if they spit them out..they're no help!!! Might as well "pray'.

I agree...water may be all there is..guess I can climb up to the wisteria and knock as many as I can in to the Koi pond....my Koi prob won't touch them...they're babied too much!! Ha Ha

Assissin Bugs eat JBs. This picture is from my friend's garden, but I saw it in my garden too. Unfortunately they are slow, so for my millions or billions of JBs I will need millions of ABs :(

{{gwi:266203}}
Olga

Right..hot soapy water...I was just wishful thinking about the Koi!

These bugs are around here...just my luck they can't "get going" for a meal!!!!

Oh, awesome, olga! That is the photo I was thinking of when I said "robber flies," glad you posted this for the right predator! You're roght, though...too few assassins for too many JB's. Blech.

There is a certain predatory wasp that was introduced in the northeast several years ago that has migrated to Maine. It lays an egg on the JB's thorax and a few days later the egg hatches and the larva bores into the beetle, killing it. You can see the white eggs on the beetles here early in the JB season. We try to avoid killing the JBs with white eggs on them.

Gardeners were quite excited when we first started seeing evidence of this wasp, thinking at last some kind of control for the JB. But it hasn't seemed to have made a dent in their population, really. For one the wasps are only active early in the JB season, leaving the billions of JBs alone that linger from August to Sept. And the JBs are just so proficient at multiplying. Only 7 years ago nearly all the JBs were wiped out in this area when their grubs froze during a particularly cold winter with no snow cover. Within 2 years you wouldn't know it, they seem to have already caught up their population levels.

Yes, it's a shame they can't thrive and multiply as quickly and stick around!!! At least we know that scientists are working on the problem and hopefully one day they will find something...another one of those "We can send a man to the moon (but we can't get rid of a bug!!!) things.

It's such an interesting irony that our gardens appear heavenly, peaceful, beautiful, lovely, but beneath the surface, everyday there is a constant war raging in the bug world.

I don't have many problems with JBs here in PA for some reason; now those damned roly-poly things are a different story. My garden is infested with those damn things.

I dread the thought of those devils arriving in about 3 weeks. Last year was the 2nd year I've had them, and they stayed until Halloween. They ignored some roses totally, but ravaged some others completely, including some clematis. It will be another busy summer drowning them in the soapy bucket of death.
-terry

Our neighbor kids used to pick JBs off the wild grape vine that grew on our natural rock seawall and toss them to waiting mallards who gobbled them up. Never could seem to persuade the ducks to pick them directly from the vines, however, nor did they notice the JBs on anything I really cared about.

It was so cute to see the baby ducklings scrambling for the treats while the parents watched and occasionally elbowed (winged??) the kids out of the way.

True Jason...always a hidden battle!! We've got roly-polys but they aren't a big problem....grandkids love 'em!!!

How about I send ya a few beetles and see if they like'em? Hee Hee You want 'em by the bushel or the peck?

Terry,
They stayed til Halloween??? Ours usually clear out around late Aug and early Sept. We're going to use grub-x again in June...got a mole and we all know what they're after. Too bad they don't like crispy beetles!!!

Hosta,
Wow... the darn ducks fly over my pond..thing's too little for them to enjoy!! I suppose at least the nasty beetles can be given credit for nourishing the little ones!! That must be fun to watch.

I'm thinking of a mechanical mantis...roaming the garden devouring them without a burp!!!! Prob not cost effective!!:((((

My husband called a place in South Deerfield Mass today about buying praying mantises for JBs. He was told that a Praying Mantis would eat one japanese beetle per day -- we would need Millions of Praying Mantises (and they're not free like the JBs are!).

We put Milky Spore and parasitic nematodes in the ground last year - by all acounts it will take a few years to notice any difference in the JB population (if we do). Also, was told "rhubarb tea" will keep JBs off roses so we're trying that this year, as well as the JB lure traps --placed well away from the plants.

We started with soapy water pails again this year, it does not have to be hot - just soapy, for the rose shaffers. JBs start the day after Rose Shaffers end and last much longer.

Well, they're here. My DH was staining the deck on Saturday and brought me one that was chomping on a clematis. It's so darned hot here now that I can't even fathom the thought of going out on JB drowning patrol.

Vicky, how do you make rhubarb tea? Does it really work?
-terry

How far away are we talking about for the traps? And how many traps do you have to use?

Many predatory insects imported to deal with certain insect infestations such as Japanese beetles turn out to be bigger pests than the insects they are suppose to control. In their native environment each insect has it's own natural enemy that keeps it within bounds. When taken from that environment it can become an invasive pest. Before we import any other insects, no matter how good our intentions we need to consider the overall result.
The cure may be worse than the original problem.
Nature in her own good time will come up with a control.
I don't let them bother me! I close my eyes to the damage and within a few weeks it lessens, eventually going away until the next year. It seems by taking this attitude, I have less damage than most.
At least I don't worry about them and let them control my every waking moment like so many other seem to do.
With all your buckets, milky spore, traps, and grub control, do you have any less damage or fewer beetles?

Every JB I drown is one less that reproduces, so yes, it matters.

They have already started appearing here (I squished about 6 of them this morning while deadheading) which is a little early, I think. I don't think we will have too many this year - I've done such a poor job taking care of my roses the past few years that there hasn't been much for them to eat. I hope they just went away in search of greener pastures LOL. I also hope they are gone by the middle of August when I hope to try to enter something in a show for the first time ever.

Many years ago when I was actively working with my roses (before life got in the way for a while) we tried the traps. They caught a lot of them, but I think they just attracted all the JBs from my whole neighborhood and we ended up with more than we had before.

Anyway, this is my first year back at serious gardening in about 4 years, and I am working so hard to bring the poor sickly roses back to life, it just kills me to see a JB munching on the one bloom of a plant.

I wish the darned squirrels would eat them. At least then they would be good for something. My neighbor puts out raw peanuts for the squirrels, and I am forever pulling peanut plants out of my gardens and pots. Grrr!

Thanks all!! I feed the squirrels sunflower seeds...costs too much these days but it's as said above...hotter here with heat indexes 111 degrees!!! I have been busy busy this week and haven't looked carefully but expect the pests any day now. I agree...I can't get out there and knock them off...not in this heat and with a chronic lung condidtion. Last year they didn't bother what blooms I had...as I've said before..the wisteria is their main meal every year...course I didn't have 14 rose bushes last year!!
I'll just grin and bear it...sigh...good luck all!!!

I wonder if deer eat JBs?

Perhaps if I hear a deer hacking I will know!

F.L.

Praying mantids also feel no obligation to stay put in your yard, or to not eat each other.

They're fascinating to watch, but not a dependable pest control insect.

Many years ago the USDA introduced a Japanese Tachinid fly (Tachinidae is a family of predatory flies) that only preys on JB's. Unfortunately it has never grown into large enough populations to be a meaningful control for JB, even though it is established in parts of the US and does prey on JB's where it exists.

In all of my years of gardening, I've never seen a mantis eat a JB. The problem is, I haven't seen any mantis this year, the mantis if they have hatched are probably too small to eat it anyway. Mantis don't reach their full growth until the end of summer usually.

Below is the link to an old album of mine which shows the life of a mantis. The year the pics were taken they hatched 6/13/02. If you look at the Don Juan tag, you'll see a baby mantis with a common house fly showing how small they are. They will be eating aphids. In a month, the mantis will be large enough to eat a fly. Then it's another month until they eat anything bigger (here in NJ anyway)

Many years ago when I was actively working with my roses (before life got in the way for a while) we tried the traps. They caught a lot of them, but I think they just attracted all the JBs from my whole neighborhood and we ended up with more than we had before.

It's one of those things, I think I would rather catch what I can, spray what I can instead of allowing them to reproduce all over town. I don't know anyone that sprays them.

Here is a link that might be useful: Webshots - life of a mantis