Attacking Japanese Beetles -- Know Your Enemy

Author's note: If you haven't read my last post: "Attacking Japanese Beetles -- Organically", please take a look at it.  You will learn more from this post if you read my last one first: 
http://theminnesotarosegardener.blogspot.com/2016/07/attacking-japanese-beetles-organically.html

JBs on Earth Song

To get to know the JB enemy, let's consider again where JBs originate.  The adult beetles mate in the process of feeding on their favorite foods (like roses, many trees and other flowers like zinnias) and you can see this happening if you observe them clustering.  The female JB then finds a lush bit of turf and deposits her eggs.  The eggs hatch as grubs and feed on the grass roots.  If enough JB grubs populate your lawn, you will develop areas of dead turf, which, when dug up, will have one-inch, white, JB grubs clustered in the roots.  That whole area of your lawn will die unless you apply grub control in the fall or early spring.  This is one of the things that golf course managers have learned and why they have been using huge amounts of imidacloprid, as the most effective grub control, over the last several years here in Minnesota.  I had this problem myself, several years ago, and applied granular imidacloprid to save my lawn.  You can bet that this is part of the reason that we have seen such an upswing in bee colony collapse disorder, which has been directly linked to imidacloprid.  One extreme example of this is Orem City, Utah, which applied imidacloprid across all neighborhoods of the city, several years ago, when JBs began to affect the floraculture and nursery industries. They even went so far as to warn homeowners not to eat any of the produce of their fruit trees, because of the systemic nature of imidacloprid. It worked, but I can't even contemplate the extent of the damage to honey bees and other beneficial insects, like lady beetles, in Utah, as the result of this extreme measure.  Here's the Utah story:
http://ag.utah.gov/home/blog/518-how-we-stopped-the-japanese-beetle.html

I also want to point out that as soon as we began to see JBs in the Twin Cities, I made the rather sizable investment in Milky Spore, with a special tubular applicator and all, and went all over my lawn and portions of my neighbors' lawns laboriously applying patches of it, exactly as specified (and I breathed-in a lot of it, as well).  I watched, hopefully, for the next few years to see what the milky spore infection would do to the JB population on my roses and I can say with certainty that it did virtually nothing to significantly reduce the population of beetles in my gardens! Oh, I'm sure that Milky Spore and a subsequent, equally expensive, application of nematodes knocked off a bunch of JB grubs in my lawn over the next few years, and they still may be doing so, but that's not where the great majority of JBs landing in my gardens are originating.

Please see quotes from the University of Minnesota about the ineffectiveness of Milky Spore here:
http://theminnesotarosegardener.blogspot.com/2015/07/the-beetles-are-coming-beetles-are.html

Fact: JBs travel amazing distances, from where they pupate, to find the plant foods they relish (like your roses).  There is evidence that they may fly as much as five miles to reach your plants, so unless all the turf within a five-mile radius of your garden is treated with Milky Spore or imidacloprid (like in Utah!) there is no way that what you alone do to your lawn will stop JBs from invading your gardens. Milky Spore and imidacloprid can protect your lawn from dying, but they can't stop the vast majority of JBs from flying your way each summer.  Save your money and concentrate on killing the JBs as they arrive, before they can lay eggs in your lawn.  As I point out in my earlier blog posts, pyrethroid insecticides, like Demand CS, work well, but they also kill beneficial insects such as lady beetles and pollinators. That is why I advocate the organic approach of manually drowning JBs. Either way you decide to go, it's far more important to concentrate on attacking and killing JBs than it is to try and prevent them from hatching on your property.

Fact: If you haven't already figured this out, JBs are amazingly canny critters. To effectively attack them, it's useful to observe what they do as they approach your garden.  When you have as many as I do, it's interesting to observe their behavior (just before drowning them!). When a JB arrives in one of my rose beds it hovers around the bed, like a helicopter, looking for a suitable place to land. Almost always, it will land on a flower or leaf that has one or more JBs already on it, or on a flower or leaf that has been previously chewed by other JBs. So, obviously, the JBs arriving in my garden, from some distance, perhaps miles away, are attracted to the scent of other JBs, presumably by the female sexual pheromone, which is all kind of amazing to me. So, it's important to get rid of tainted leafs and flowers, whenever possible.  I know how hard it is to pluck a brand new bud that has two JBs imbedded in it, but it's important to do that in order not to let it attract incoming beetles (I did it just a few minutes ago and it is painful).  Interesingly, when they can't find an old leaf or flower to land on, they seem momentarily confused and can be easily picked off. Also, believe it or not, while they are hovering around looking for a place to land, I have been quite successful in grabbing them in mid-air!  That actually makes the whole exercise kind of fun once in a while.

The good news is that JB season should soon be over.  They started early this year (June 19th) so they should soon be finished. Better days ahead.

Jack Falker
@mnrosegardener
July 21, 2016

Attacking Japanese Beetles--Organically

On the theory that a picture is worth a thousand words, here's what organic JB control looks like:

That's one day's catch of JBs in my garden; a couple hundred of the monsters, now dead, organically.

There is more to this than meets the eye.  When you attack JBs organically, rather than with pesticides, you not only spare all the important beneficial insects in your garden, especially lady beetles that do so much for us, but you also enhance the health of your garden.

Here's why.  When you knock JBs off your plants into soapy water, or pick them off with your fingers every day, you should naturally be dead-heading your roses at the same time. Any bloom that has more than one JB on it, or appears to have been previously chewed by multiple JBs, should be plucked off between your thumb and forefinger and thrown away (after you drown the JBs, of course).  That's because those blooms, no matter how nice they still might look, likely have the JB sexual pheromone on them and will attract male beetles from long distances away. Actually, the old-fashioned, thumb and forefinger method of dead-heading is very effective in encouraging rapid growth in your garden, so that's what you're accomplishing here.  Here is one of my early blogs about what my mother taught me about dead-heading:

http://theminnesotarosegardener.blogspot.com/2012/06/deadheading-or-things-my-mother-told-me.html

The attraction of the JB female sexual pheromone is also the reason that JB traps are not a good idea.  They contain the JB sexual pheromone as an attractant and when they fill up with JBs that pheromone is multiplied hundreds, if not thousands, of times by the JBs themselves.  And it's important to understand that the JB is a very sophisticated organism (really all insects are, but we miss that with our kill, crush, destroy mentality). There is recent evidence showing that JBs actually travel as much as five miles, from the turf in which they pupate, to the foods they seek (especially roses).

That's also why I think it's fruitless to try and control JBs with organic Milky Spore on your lawn.  In deference to my compatriate rosarian friend, Paul Zimmerman, whom I quote below, It's no doubt  useful in killing off JB grubs, in your lawn, over time, but it really can't stop JBs from attacking your rose garden, simply because they come in hordes from up to five miles away.  So, unless everyone in a five mile radius uses Milky Spore (especially golf courses), it does not help and you have spent a lot of money (it's pretty expensive).  I used it extensively, years ago, when JBs first found their way to Minnesota, and it did not help.

Please read one of my most recent blogs on JBs which includes quotes from the University of Minnesota on both JB traps and Milky Spore:

http://theminnesotarosegardener.blogspot.com/2015/07/the-beetles-are-coming-beetles-are.html

Last week, I received a question from Michelle, in Virginia, who was at her wit's end with a huge infestation of JBs and was about to succomb to the use of the pyrethroid, Demand CS (Lambda Cyhalothrin), which, as I mention in my blog above, does a pretty good job of deterring JBs but also wipes out beneficials and pollinators in the garden.  Not having experienced her level of JB infestation in the middle-south, I referred Michelle to Paul Zimmerman, who is a dedicated organic gardener in South Carolina, for his advice.  Paul posted this response on his "Paul Zimmerman Roses" Facebook page.  While we don't necessarily see eye-to-eye on the use of milky spore and traps (but I know Paul will see my logic above), I really like his ideas on garden clean up, deadheading and the use of companion plantings for both insectary benefits and attracting JBs away from the roses.  This is really the essence organic gardening.  Here's Paul's answer:

"Regarding Japanese Beetles. Milky Spore bacteria has been proven to work so yes, use it. Takes about 2-3 years to become totally effective but it's a good first step. 

However, here is how I've dealt with the problem for the last 16 years. I'm an organic garden so I don't use insecticides of any kind. I build a host environment for beneficials and let them take care of it. That works great for all native pests but of course JBs are not native so they have no native enemy.

Around here the JBs appear in late early June and continue for around 4 weeks. For me this is after my spring flush. When I see the JBs out in full force I use that as an opportunity to clean up my garden from the spring flush and get it ready for the fall one. I go through the roses, trim them back, clean out dead wood, weak wood and do a thorough deadheading. Essentially I'm cleaning out a lot of the parts of the roses the JBs like during my normal maintenance.

As the beetles start to wind down the roses wake back up again. I'll go over them again to do another light clean up and that's that.

Another thing I've done over the last several years is adding lots of perennials to my gardens. In and amongst the roses. This was for aesthetics but more so to help create that host environment for beneficials. I've noticed the JBs seem to flock to the perennials and while there is some damage it's not as noticeable as on the roses.

Essentially I work with them that way. Use their arrival as part of normal summer cleanup and plant other plants they may find more attractive.

PS. Regarding traps. They do help but hang them away from the garden areas."

Seconding Paul's statements above, I have a lot of companion plantings in and around my rose gardens for both insectary and aesthetic purposes. For example, I have patches of dill, oregano and cilantro growing in every one of my rose gardens, which are inundated by beneficials.  I also have two beds of zinnias growing close-by and that's where the JBs really gather.  Believe it or not, I've actually found something (zinnia foliage) that JBs like more than roses and I'm actually drowning more JBs on the zinnias than on the roses!  Lots of chewed leaves, but these plants are fast-growing right now and can keep ahead of the JBs. I also have several big shrub roses planted in my vegetable/tomato/insectary garden, away from my main rose gardens, that attract clusters of JBs, which are very easy to drown, eight and ten at a time.  The shrub they really like is David Zlesak's "Above and Beyond" and, since it's done blooming for the year, I have fully dead-headed it and cut it back, which has made if far less attractive (exactly what Paul was talking about above).

So, as I point out in my recent blog post "The Pesticide-Free Rose Garden",
http://theminnesotarosegardener.blogspot.com/2016/05/the-pesticide-free-rose-garden.html, the key element in organic rose gardening is PATIENCE! Remember, as Paul points out above, JBs only last about four weeks and, if you work hard to deter them organically, they ultimately go away, leaving you with lots of beneficials and pollinators, as well as fully dead-headed and healthy roses for the rest of the growing season (also a great time to fertilize again).  My JBs started early this year, around the middle of June and, as we approach the middle of July, I think I can see them beginning to taper off. Remember that every JB you drown right now is a monster-bug that can't breed more monster-bugs for next year.  I particularly enjoy taking them down when they are atop one another, stopping the breeding cycle.  Tonight at dusk, I nailed two breeding pairs on my zinnias, with my bare right hand.  It felt good to feel the four of them wriggle before they hit the soapy water. Take that you monsters!

Jack Falker
July 9, 2016