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