How to Control Japanese Beetles
Every Saturday, visitors to the Pakatakan Farmers' Market stop by to check on the progress of the Pizza Garden, which is overflowing with all the ingredients needed to make a tasty tomato sauce. The one question that gets asked most is, "How do you keep animals from eating everything?" Apparently a major obstacle to growing vegetables is predation by critters.
Deer don't like tomatoes, peppers and herbs. No bunnies have been sighted in the vicinity. A groundhog lives under the Round Barn, but hasn't caused a problem. But there is something devouring the basil: Japanese beetles.
The insects showed up at the end of July and promptly turned the basil plants' luscious top leaves into an unappetizing skeletal lacework of stems and veins. The damage stopped there because of effective control techniques.
Know the Enemy
Popillia japonica is an invasive species that hitched a ride on a ship and disembarked at a U.S. port sometime before 1912, when inspection of commodities began. The beetles are not destructive in their native Japan due to natural predators and limited grassland. Our country's abundant lawns provide the perfect incubator for Japanese beetles in their larval stage. Females only lay about 3 eggs at a time, but may mate and burrow into the grass repeatedly, depositing up to 60 eggs by the end of summer. The white grubs live underground for 10 months, nibbling on grass roots. In cold climates, the larval stage may last an extra year. The grubs pupate and emerge as iridescent beetles in July. And that's when the carnage begins.
Infestation
It starts with a couple of beetles on a plant in full sun. As the insects feed, the plant sends out a distress signal, which unfortunately attracts more beetles. That's why hordes of beetles will often single out one plant, feeding until all that's left is a pathetic skeleton. Removal of the initial beetle scouts helps prevent the decimation of your landscape. Harvesting the basil leaves and pinching back the tops to prevent flowering coincided with the initial attack by the beetles. The youngest basil plant was left untouched by both gardener and bugs.
Simple Countermeasures
Don't be tempted to purchase traps. They only attract more beetles to the area. (One visitor to the Pizza Garden said with a wink, "The only way traps work is to not use them yourself, but give them to all your neighbors.") Fortunately, the equipment to combat adult Japanese beetles is simple and inexpensive. Here's all you need:
- A cup of soapy water
- A spray bottle with equal parts apple cider vinegar and water
The squirt of dishwashing liquid is important. Beetles merely perform the backstroke for hours in plain water, but suds cause them to perish quickly.
Going Ninja
The best time to dispose of Japanese beetles is in the morning when the insects are sluggish. Approach with stealth (Ninja costume optional), as commotion will cause the bugs to fly away. Carefully remove the beetles and drop them in soapy water. As beetles feel the plant being jostled, they let go and fall back. You can hold the cup under the leaf and catch them in the cup. Some will escape to the ground. Remove all the beetles you can from the leaves, then hunt down the fugitives hiding in the mulch. Their shininess makes them easy to find.
Success!
The first day of beetle control, 60 insects were dispatched to their sudsy demise. The next day, there were 12. The next day, 7. The leaves were then coated with the vinegar spray, applied in late afternoon to prevent sun scald. Number of Japanese beetles the following day? Zero!
Controlling Grubs
Spraying your grass with milky spore will prevent future generations of Japanese beetles. Other natural controls include nematodes and Bacillus thuringiensis, which destroy all lawn-eating grubs, and which can be purchased through gardensalive.com.
Natural Predators
Various animals prey on the beetles. One is the anchor bug, which is a stink bug dressed in black and orange with an anchor shape on its back. Other predators include tiphid wasps, tachinid flies, ants, ground beetles, moles, skunks and raccoons.
Iridescent Aftermath
One online source recommended scattering the dead bodies of beetles to ward off others. After ensuring the beetles were truly deceased, the soapy water was poured around the basil plants, leaving a trail of metallic corpses in the mulch. Their gold wings and teal bodies sparkled like jewels. What a shame something so beautiful has to be so destructive.