Here it is! That time of the year again in New Jersey when the Japanese Beetles, Popilla japonica, emerges from the ground to wreck havoc in our gardens! I have seen these small, six legged beetles on rose bushes, crape myrtle, weigela, cherry trees and various flowering plants. Japanese Beetles feast on leaves and flowers; whereas Japanese Beetle larva feast on roots of grasses. Japanese Beetles are easy to identity as they hide in flower blooms. They have a green head and thorax and their abdomen is a bronze color. They start emerging from the grounding during this time of the year and in order to control them, we need to understand their life cycle!
One of my favorite charts ever when it comes to the Japanese Beetles is on the back of any St. Gabriel’s Milky Spore product line.
If you look at the chart, we are just out of June and entering July. During some point of the month of June, the larva goes through a metamorphosis. The larva pupates and emerges from the ground to feast off of our plants and to mate. The adult beetles live between thirty to forty five days. One Japanese Beetle female can produce sixty eggs! The females lay their eggs in the ground in August. The eggs hatch into a C-shaped larva that is the color of a clear white. The larva actively feed on roots from August to September before they make their way down to hibernate in the soil from October to March. Then in April and May, the grubs start actively feeding again and go through their metamorphosis entering June. Then the cycle starts all over again!
There are different types of products that you can use to combat Japanese beetles and their grubs. The products that I will be talking about are products that my garden center stocks during the year. The products are in order on when to apply it during a calendar year. Products have certain time frames when they can be applied during the year. It’s always important to follow all instructions and safety regulations on the back of any application product whether it is a spray or a granular.
The first one is Milky Spore. Milky Spore is an organic option for grub control. Milky Spore is a beneficial bacteria that reproduces in the soil. The beneficial bacteria kills grubs and it stays in the soil. You apply this three times a year: Spring, Summer, and Fall for two consecutive years. By the third year, it is in the soil and ready to kill grubs.
The second one is by BioAdvance, formerly known as the Bayer company, Seasons Long Grub Control with Turf Revitalizer. The active ingredient is Imidacloprid, also known as Merit. Imidapcloprid is a type of neonicotinoid which is harmful to the bees if ingested by them. This one you can apply during May to August and it stays in the ground for the whole year. When we apply it, it kills the grubs who are already in the soil as they actively feed in April and May and then kills out the grubs who hatch in August. I tell customers to apply this in May when they are active in the soil.
The next product is one again by BioAdvance 24 Hour Grub Control. The active ingredient is Dylox. Dylox is an insecticide that immediately kicks in when watered in or after a rainstorm. Dylox is really toxic to the environment but stays in the soil for 48 hours. This product is to apply in late August to early September as thee new grubs just hatched; then next spring I would either start up with the Milky Spore product line or go with the BioAdvanced Seasons Long Grub Control. Both BioAdvanced products are non organic.
Not only are the lawn applications a good practice, but we can also follow up with setting up Japanese Beetle traps! The way that these traps work is that the pheromones attract the beetles into the trap, they go into the trap bag, and they cannot get out. They just die in the bag. Make sure you put up your traps away from the desirable plants and ten feet apart! You may need to change out the trap bags and put in new pheromone bait. Make sure you stock up on those extras! We need to take in consideration that even though we treat our lawns, Japanese Beetles can fly from your neighbor’s backyard into your backyard. The traps are vital.
The last piece of the puzzle to control Japanese Beetles are sprays. Some excellent sprays that you can use is GardenTech Sevin, Bonide’s Eight, Bonide’s Captain Jack’s Deadbug spray, Bonide’s Tomato and Vegetable spray (my FAVORITE application product), and BioAdvanced Insect, Mite, and Disease Control. Bonide’s Captain Jack’s and Bonide’s Tomato and Vegetable spray are both organic options. These products are great to apply once a week to control Japanese Beetle damage. They cannot reverse the damage but it will kill on contact.
This short lived season with the Japanese Beetles can be controlled very easily with the right products and the right knowledge! I hope you enjoyed my post to help you through this short lived season and I hope I helped you pave a pathway for future control! Have a happy weekend!