So one day your roses were covered in colorful blooms and then the next day… gone! Chances are the culprit is the dreaded Japanese beetle. It’s late in the season for beetle damage here in the Lakes Region, but my knock out roses are still being devoured. The telltale sign, along with an extreme lack of blooms, are skeletonized leaves and even complete defoliation. Usually, the demons can be caught in the act. Japanese beetles also love to eat rosebuds – every last one that you’ve been anxiously awaiting.
If you are unfamiliar with Japanese beetles, they have shiny, metallic green and copper colored bodies – kind of pretty in the worst sort of way. They are roughly 3/8-inch long and 1/4-inch wide.
WHAT DO I DO ABOUT THEM?
The best defense is a good offense. Japanese beetles are the adult stage of grubs that are found in your lawn earlier in the season. A good lawn program to control grubs applied early in the spring before the beetles emerge is your best bet. Watering, fertilizing and general good horticultural practices will also help reduce the damage caused by Japanese beetles.
Inevitably though, the beetles still come and there are a couple of options to hold the major damage at bay. Spray affected plants with a pyrethrin-based insecticide the minute you notice them. This is a safe and effective control that can be used on flowers and vegetables alike. It will help to control other pests as well. To make every effort to cause no harm to honeybees with these products, do not apply during hours when bees are actively visiting the flowers.
Neem oil is an “antifeedant”, which when used early on can be an effective tool to reduce feeding. Chances are you will have to reapply either of these options if the beetles last as late in the season as they are this year.
Another helpful, but disgusting option, is to hand pick them first thing in the morning when temperatures are cooler and they move a bit slower and drop them in a bucket of water containing one tablespoon of liquid dishwashing detergent. If you are diligent about this it is a very effective way to clear your garden of these pests.
Japanese beetle traps are helpful if you have the ability to place them far from your garden. They actually have an aromatic chemical attractant that brings them to the trap so you don’t want to hang it near the plants you are trying to preserve.
Whatever option you choose – choose something fast! Timeliness and thoroughness of application are very important in controlling the damage or at the very least, keeping it to a bare minimum.