Maybe some good news for our Japanese Beetles friends

aachenelf z5 MplsJanuary 24, 2013

I was looking around to see if there was any info on cold temps and its impact on Japanese Beetle populations and found the following:

"Although grubs migrate down to avoid freezing temperatures, some mortality may still occur over the winter if rapidly changing conditions prevent the grubs from moving far enough to escape lethal environmental conditions. For example, sudden cold spells with little snow cover often cause high mortality.

A heavy snow and thick sod cover usually result in grubs� being closer to the surface and surviving with only low mortality. They tend to move deeper in relatively barren soil. Lack of substantial snow cover on barren soil typically results in extremely high grub mortality. Japanese beetle grubs are killed at soil temperatures near 15�F and die when soil temperatures are consistently around 32�F for 2 months."

With no snow cover this year and a week of lows in the negative numbers and highs barely above zero, I will be curious to see if I see less of them next summer.

Has anyone noticed that in past years?


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Kevin, I think I mentioned something similar in another thread re winter weather. It is my hope as well that the very cold weather we are experiencing this week coupled with no snow cover will result in noticeable decline in the 'bad' bugs...specifically for me the JBeetles and also the Sunflower Moth larvae which has ravaged the cones in my echinacea the past two seasons.

I am just not sure if 5 days of frigid temperatures is enough to 'crush' them.

This post was edited by rouge21 on Thu, Jan 24, 13 at 14:58

    Bookmark   January 24, 2013 at 11:07AM
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Kevin, I will be waiting to see if that's the case. We've had many less Japanese Beetles the last two summers, and last year, I hardly saw any at all. Before that, they were everywhere. I stopped buying the JB Traps about three years ago after reading that I might have been the neighborhood JB drivethrough by using them.

I have a local friend who used milky spore on a large lawn several years ago and I don't think she was too happy with the results. It was expensive and a lot of work to do. And she still had grub problems.

I hope others will post this summer to let us know what kind of JB season it was for them where they are.

We have a dusting of snow right now along with the cold temperatures so the ground will probably be really cold with no snow insulation.


    Bookmark   January 24, 2013 at 4:08PM
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aachenelf z5 Mpls


"I am just not sure if 5 days of frigid temperatures is enough to 'crush' them."

I'm not sure either, but our frigid stuff came very rapidly, so hopefully they didn't have time to burrow deeper. I would imagine the grubs were cold and slow to begin with, so maybe their movements were limited.


I never quite understood the logic of using milky spore. It might kill the grubs in your own yard, but the beetles certainly don't stop at property lines. If all your neighbors don't use it too, the critters are going to fly into your yard anyway. Heck, they probably come in from miles around.

Well, I suppose I take that back. If the grubs are causing damage to your lawn it makes sense to use some treatment. That is if the stuff works.


This post was edited by aachenelf on Thu, Jan 24, 13 at 17:37

    Bookmark   January 24, 2013 at 5:30PM
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Well, we had a mild and non-snowy winter last year and a fairly average winter the year before that, and both times the ensuing JB population was far below what I'd seen in previous years.

Single-digit cold with no snow cover may or may not have an impact on our grubby friends, but I'd happily settle for the third year in a row of low beetle populations.

    Bookmark   January 24, 2013 at 6:33PM
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ken_adrian Adrian MI cold Z5

the heck with the bugs..

am hoping for all the nibblers and tunnelers ... to die a cold hard death ...

mice.. voles.. moles ... you name it... bugs would just be a bonus ....

last years ridiculously mild winter was horrid in regard to population explosions .... regarding such ...


    Bookmark   January 24, 2013 at 6:40PM
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Ken, if I lived closer to you I would lend you my very accomplished 'mouser'. It may not be that he gets as many of these rodents in the winter but rather instead he significantly depletes the population in the summer.

This post was edited by rouge21 on Fri, Jan 25, 13 at 8:43

    Bookmark   January 24, 2013 at 8:15PM
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I think you might be right about the milky spore. My friend used the teaspoon dump every so many feet while walking the entire yard method. It took forever to do it, and she still complains about grubs. I can assure you that her neighbors did not treat their yards.

Today, we've had quite a significant addition of snow to the dusting I mentioned above. The temperatures are going to moderate now, to the point where we are going to see 50 degrees next week. Crazy weather for sure.

I'm with Ken - I want rid of all of the mice, moles, voles, bugs, etc.

    Bookmark   January 25, 2013 at 12:11PM
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Thyme2dig NH Zone 5

I'm with Ken too. The rodents are the worst!

Maybe I've gone the entirely opposite direction in fighting the japanese beetles, and perhaps they ultimately won the battle? Over the years I have removed any japanese beetle magnets from my yard. I used to have a rose garden in front, but the japanese beetles came in droves. Weren't my co-workers ecstatic when I brought in a rose bush for eah one! They also really liked a pussy willow I had and purple leaf plum. I'm sure there are other plants that I've removed and just forgotten about. I have hardly any japanese beetles coming anymore, but I really did like some of those shrubs.

    Bookmark   January 26, 2013 at 8:41AM
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north53 Z1b MB(zone 1b Canada)

So far we haven't experienced the Japanese beetle. Here's hoping the frigid winter we've had so far will keep them away. There does seem to be a correlation between a mild winter and outbreaks of infestations though. Last year we had an unseasonably mild winter...great fun for most people, but in the summer that followed we had some serious scourges. In my yard the worst was some kind of cutworm that devastated many perennials and annuals. It didn't seem to be fussy and could destroy a plant overnight. It was worse of course for the farmers who had crops destroyed.

    Bookmark   January 28, 2013 at 11:09AM
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terrene(5b MA)

Generally the Japanese beetles have tapered off in this area. Although I did see a number of them on the Purple Loosestrife that grows in the wetland areas in the neighborhood. Good beetles! Eat the terrible invasive plants! In fact, I have a somewhat weird idea to use the Japanese beetle traps to lure the beetles to the Purple loosestrife that is invading my favorite milkweed field where I collect Asclepias syriaca for the Monarchs. Perhaps they will curb its spread a little?

Meanwhile, I noticed that the mosquito and tick population was greatly reduced last summer, after the nearly snowless winter last year. Hoping for a repeat this summer.

    Bookmark   January 28, 2013 at 8:14PM
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garden_crazy(z5 N IL)

I wish the Chipmunks would go away. Every year there are more and more and more. A master gardener friend told me to put gumballs out for them. They love them but cannot disest them............. I can't bring myself to drowned them.
I put milky spore down -broadcast- about 1 acre. It made a HUGE difference in the population. I can't say that there have been other environmental issues that would have had a great impact on them. -I put it down about 5-6 years ago, backyard only (cost/test). -All my plants are pretty much in the backyard. Even though it is pricey, one application lasts for so many years/

    Bookmark   February 18, 2013 at 12:08PM
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Well, last year the Japanese Beetles came late -- I thought maybe they forgot about us like the mosquitoes did but they did arrive in late July. I sprayed them with 'Bug Stop' by Spectricide and I never saw such a good result with any other killer! I only had to spray them once and didn't see them again.

We had no rain, however to wash it off the leaves but my perennial Hibiscus was not bothered and neither were the fruit trees.

    Bookmark   February 25, 2013 at 3:50PM
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