Friday, August 17, 2018

My latest (crazy?) defense against Japanese beetles

The butterflies are magical, but they're not my only garden visitors....

It's official: the Japanese beetles are out of control. They're ruining my roses, hollyhocks and other flowers. I know they'll be gone before too much longer, but they've been absolutely horrendous this year and I don't see them being any better in future years.

I didn't mind them so much when I had few roses near my house, but now when I sit in my new Paradise Garden each evening surrounded with roses and other flowers, seeing the damage and ugly clusters of beetles really bothers me. I think my new garden is probably the nicest garden I have ever made, and I'm not going to give it up or stop growing roses in it, so what to do?

It's magical in the evenings, filled with butterflies, hummingbirds and scented flowers. The JBs hadn't gotten this rosebud yet for some reason -- but the next day it was destroyed.

This climbing rose growing on the arch over my front gate was repulsive! This foul sight greeted me every time I came home until I pruned the plant down almost to the ground in disgust.

My 'Sharifa Asma' rose, known for its scent and
beauty, was utterly defiled by the disgusting beasts.

Even the marigolds planted in my Paradise Garden weren't immune -- I was surprised, as they have long been thought to act as a repellent to other insects. But the JBs love them (although they don't seem to cause as much damage to the leaves and flowers as they do on roses).

Last month, I posted about the Japanese beetle problem, and at that point I felt pretty hopeful about my efforts to control them, but I think that was unrealistic:

1. Every evening I walk around with a container of warm soapy water and use a butter knife to knock off as many JBs as I can find into the container. This does seem to somewhat reduce the damage done by them, and it makes me feel better -- but this is not how I want to spend so much time in my gardens.

2. I don't want to use systemic insecticides because I don't want to hurt the bees, and they only reduce the problem anyway, not eliminate it. So instead, I sprayed an organic pyrethrin-based insecticide at dusk, after bees go to sleep. The pyrethrin did kill the JBs that were on the plants -- the ground under the roses was littered with their bodies the next day. But more showed up the next day and didn't seem to be affected by the residue. Also, it made my Paradise Garden smell like insecticide, not sweetly-scented flowers. Yuck.

3. I planned to treat my lawn for JB grubs this month to try to reduce their future numbers. But my two acres of lawn would have cost probably $150 to treat, twice a year, and I found out that the JBs can fly 3-5 miles, so more will simply come from miles away. Useless.

4. I treated my lawn with milky spore treatment about five years ago, but I've read that studies have shown it doesn't work very well. Ditto nematodes.

5. I wondered if a simple repellent existed, and I was excited to read that steeping red cedar planks in hot water would yield a spray that some people swore by -- free and easy! I tried it and I could certainly smell the cedar spray -- but the JBs didn't seem to mind it at all, and in fact the three test plants I sprayed had even more beetles the next day. Aaggh!


I apologize for my pessimistic attitude, but the more I research Japanese beetles, the worse this story gets -- next year and every year after that will probably be just as bad, if not worse. And my aesthetic problems with them pale in comparison to others' more serious problems. They cause millions of dollars in damage to crops and ornamental plants; last year, an Iowa winery lost $20,000 of their grape crop to the buggers. They're also destroying milkweed habitats that monarch butterfly populations depend on to survive. They only arrived in my area about a decade ago, and didn't seem so bad a few years ago because the unusually cold winter of 2013-14 knocked back their numbers. But I think this rebound is the new normal.

And it's not just a problem for Northeasterners and Midwesterners; Portland, Oregon has been quarantining and desperately trying to eradicate a suburban infestation of Japanese beetles that threatens the Pacific Northwest's huge agricultural sector.

Steadily moving west....

And they've already spread to Europe too: JBs were found in a nature reserve in northern Italy near Milan in 2014, and by last year they had already spread to southern Switzerland. Etymologists believe most of continental Europe, the UK, Ireland, parts of Australia and New Zealand are all suitable habitats for them. The Netherlands has long been dreading their arrival; since the 1950s they've had Japanese beetle traps at the international airport in Amsterdam to monitor for them. English gardeners had better enjoy their national love affair with the rose while they can.

Their invasion is inevitable everywhere, except very dry and extremely cold areas  -- I only hope that someone really smart will figure out how to eradicate them easily and cheaply.  They're invasive pests that shouldn't even be here, and we should target them for total continent-wide eradication, if it can be done without harm to other species or the environment (genetic engineering to render them sterile may be the safest way to do this).

But back to my own (admittedly minor by comparison) problem right now....

My Latest Desperate (Crazy?) Idea

If insecticides, hand removal, grub treatments, milky spore and repellents don't work, what else? Some people have put netting and row covers over fruit trees, berry bushes and grape vines, but I don't want to have nets over each of my rose bushes and on every marigold and dahlia, preventing me from enjoying their beauty. How ugly would that be?

But then I started to wonder: Could I put a very big temporary net over my entire Paradise Garden? That's where most of my roses are and where the JB damage bothers me most. I looked this up online and couldn't find any examples of other gardeners who have done this -- maybe that should tell me something.... I saw pictures of bird netting enclosures, net cages for fruit gardens, and netted cat enclosures ("catios"), but no beetle-netted flower gardens.

I'd need a pretty big net to cover my roughly 24'x27' Paradise Garden. However, I looked around and found beetle net sold in rolls 100' long by 14' wide on

And how could I support the net over my garden, so that I could still go inside and enjoy my garden? I'd need some structure that's inexpensive, easy to set up and take down, and not hideously ugly. I hit on something that I hope will work:

It's not too ugly, I think, for a temporary structure. It's a 10x20-foot shade canopy or carport frame (it comes with a cloth roof, which I'm not using), that I found at a local home improvement store for only $80.

When the net arrived last Friday, I unrolled all 100 feet of it out in our big yard, and cut it into three sections, each 33 feet long and 14 feet wide. I then sewed those three sections together by hand using nylon twine, making a 42-foot long, 33-foot wide net.

Getting the net over the top of the structure all by myself (family's away camping) wasn't the hard part. After that was done, I spent two days attaching grommets to both sides of the net, so I could attach the net to wires strung in front of my house and along our front fence, so the net won't blow away when it's windy.

It could look worse. I like to think of it as being like a Bedouin tent, in keeping with the Islamic-style Paradise Garden theme.

I have no idea if this is going to work. I've read that JBs don't usually fly along the ground, but swoop down from up high when they smell pheromones emitted by female beetles already eating flowers and foliage. So having a net over the top of this garden may exclude new ones from entering.

There were still a fair number of them already in the garden though, so I've been working overtime with the soapy water bucket to eliminate as many as possible from inside the net. I have noticed a lot fewer of them inside the tent after several days, and I see some on the outside of the net that can't get in. :-)

Hah! You just stay out there!

I'll only have to put up this temporary net for 8-10 weeks, from mid-June until late August each year. Then, I'll pack it away carefully until next June.

I feel a bit bad keeping the butterflies and hummingbirds out (they were so magical!), but they'll have free rein in this garden all during autumn, and I have numerous zinnias, phlox and other nectar-rich plants in other parts of my garden for them to enjoy during mid-summer. If the JB's must have those plants too, it won't bother me so much, as long as I have my safe rose sanctuary in my netted Paradise Garden.

If this works, it could be the best way to protect roses in JB-infested regions:

  • safe for the environment and other insects
  • temporary
  • less expensive than treating large areas of lawn for grubs
  • more aesthetically attractive than netting that places a barrier between us and our plants 
  • and effective!

Welcome inside the Bedouin tent.... I cut a door flap in the front of the net, to make it easier for people (not beetles) to enter.

I'll move a few more roses from other areas into the PG, and I think I'm just going to have to get rid of all my climbing roses, since needing to cut them back drastically each summer pretty much eliminates the entire purpose of climbing roses. I'll probably replace them with clematis or some other flowering vine that blooms before the buggers arrive.

I'll keep you posted about the effectiveness of my crazy big net.

Until then, I hope you have been enjoying lots of lovely summer flowers, not munched by insects, in your own gardens. Thanks for reading my very long post! -Beth

Look, no beetle clusters! Only lovely roses and sweet peas and petunias.
Maybe the net's not so crazy? :-)