How to Control Japanese Beetles In Your Organic Vegetable Garden

What's green, shiny and buzzes all over? Unfortunately, the answer to this question is not as amusing as you might think. The answer is Popilla japonica, the Japanese beetle. If you live in the United States, and you are reading this during the months of May, June or July, this pest is likely to be hard at work in your organic vegetable garden at this very moment. Japanese beetles can be found happily munching on trees, ornamental plants, lawns and vegetable plants.

5 Organic Ways to Get Rid of Your Japanese Beetle Problem

1. Avoid growing their favorite plants. These include strawberries and eggplants.
2. If you see them on your plants, pull them off and kill them--as far as Japanese beetles are concerned, the more the merrier--the more you already have, the more you'll get.
3. Don't use pheromone traps (those plastic bags that get full of beetles--while attracting legions more than they catch).
4. Use biological control agents such as nematodes and milky spore bacteria to control beetles.
5. Keep your produce harvested--overripe and rotting produce attracts beetles.

I'll start with the good news: it is possible to reduce your garden's Japanese beetle population by using organic methods and you don't have to completely eliminate this pest in order to save your plants. The bad news is that Japanese beetles are good flyers and they are glad to move into your garden from up to 5 miles away if they sense that it's a good place for them to be.

So, first of all, let's look at what makes your organic garden desirable to them. It's probably one of two things:

1. They sense (through their ability to detect pheromones) that other Japanese beetles are having a great time feeding on your plants and finding mates. The more beetles you have, the more you are likely to get.

2. They sense (how is a mystery) that there are damaged, diseased or malnourished plants or rotting fruits and vegetables that will be easy pickings for them.

Now that we know what makes them want to move into your organic garden, we can create a strategy for discouraging them. According to the University of Kentucky Cooperative Extension Service, "When you remove beetles daily by hand from a plant, only about half as many are attracted to that plant compared to those on which beetles are allowed to accumulate." Japanese beetles tend to congregate in clusters that can easily be knocked off of your beloved plants into a bucket of soapy water where they will drown. Squishing them is an option for those of us who feel more aggressive towards them.

Removing the beetles will also decrease the amount of damage they do to their host plants. This further decreases the amount of beetles that will migrate to your organic garden. Harvesting your fruits (strawberries, apples, etc.) and vegetables (peppers, eggplants, tomatoes, etc.) before they become overripe or begin to rot will also decrease the number of beetles that you attract to your organic garden.

Strawberries and eggplants are two of the many garden crops that Japanese beetles are attracted to. Covering these and other affected crops with floating row cover will help but will also interfere with the pollination of these crops.

In your battle against the Japanese beetle, please refrain from using the popular pheromone traps--these attract many more beetles that they catch, leaving you with more beetles than you started with. If you absolutely can't resist using them, keep the traps well away from your favorite garden plants so as not to lure the beetles right to them.

The shiny adult Japanese beetles are most active for 6-8 weeks in early to mid-summer. By the end of their annual reign, they have laid their eggs and the grubs have hatched and have begun feeding. During the winter, these grubs will burrow into the soil and await next summer's bounty.

The biological controls available to organic gardeners can help keep these grubs in check. These controls include parasitic nematodes, Bt, parasitic wasps and milky spore bacteria. These controls can often be purchased in garden centers or through mail-order bio-control catalogs.

Luckily, the beetles are only in full force for several weeks at a predictable time each year. We can use our knowledge about Japanese beetles and their habits to beat them at their own game. Now, let's get to work and take back the summer!


For More Information:

Managing Adult Japanese Beetles (contains list of Japanese beetle resistant landscape plants).
http://www.uky.edu/Ag/Entomology/entfacts/trees/ef409.htm

This USDA site contains extensive information about biological pests of Japanese beetles
http://www.pueblo.gsa.gov/cic_text/housing/japanese-beetle/jbeetle.html

Biocontrol Website--The Biocontrol Network Sells Bt and Other biological controls
http://www.biconet.com



See Also:
There's a Goosefoot in my Garden
It's Easy to Grow Great Garlic
How Does Your Garden Grow Part One: Getting to Know Your Soil
Bountiful Basil