Japanese Beetle Season Has Begun. Do you have a problem with Japanese Beetles or are they just moving into your area recently? Maybe you don’t see the beetles, but suddenly your flowers and leaves were skeletonized overnight?
Every June or early July in the Midwest (though it may vary depending upon where you are located), we gardeners weep as we see the tell-tale holes and damage to our prized blooms and leaves. When Japanese Beetles (Popillia japonica) move into an area, they have a voracious appetite and can destroy everything in their wake!
Why is the Japanese Beetle harmful?
As larvae, Japanese Beetles feed on the roots of many varieties of watered turf grasses. The adults consume the leaves of a wide range of plants.
The shiny brown beetles have an iridescent green sheen and are actually very pretty! Unfortunately the damage they wreak on your prized Roses and the costly damage to food crops have vilified them immensely!
Commonly found feeding on the newest growth of plants they like. They eat the tissue between the veins in the leaves leaving the leaves looking skeletonized or like brown lace. Plus these beetles can completely mow down entire blooms.
These little grubs are the reason for the brown spots and sparse areas that develop in your yard. By chewing off the roots, your grass isn’t able to take up water and as a result, dries out in the heat and drier portions of the summer months.
What crops do Japanese Beetles eat?
Certain plants are huge magnets for Japanese Beetles. They eat the flowers and leaves, or even the fruit, of more than 300 species of plants!
Their garden victims include: Legumes like beans and peas, Strawberries, Tomatoes and Peppers, Grapes and Hops, everything in the Rose family, some Maple trees, Linden trees, fruiting and flowering trees such as Cherry, Pear, Plum, and fruiting Peach trees, plus your Raspberry Blueberry and Blackberry plants are all susceptible, among many others!
Japanese Beetle Life Cycle
Depending upon where you live, the beetles are first noticed in late June or early July, sometimes emerging as early as late May! Grubs can be very drought resistant and simply dig deeper during drought, but on the flip side, they tolerate high soil moisture just as easily! Excessive rainfall or watering your lawn frequently won’t seem to phase them. Grubs are active and feed on the roots of your lawn when soil temperatures are over 60°F.
This part of their life cycle does give you a chance at destroying the grubs in watered lawns and large expanses of turf areas like golf courses and watered parks.
Adults are great fliers and can traverse several miles to feast and find a mate, but only live for only about 60 days. During that time they lay eggs in your lawn and start the cycle all over.
What can you do to get rid of Japanese Beetles?
What is a natural way to get rid of Japanese Beetles? Probably the easiest and most environmentally-friendly way is to physically remove the bugs from the plants - keeping in mind that they continue to hatch for 6-8 weeks!
- Handpick them off the plants and drop them in a bucket of soapy water
- Hold a bucket of soapy water under branches and shoots - knocking the bugs off into it to drown. These insects' main defense is to drop to the ground and try to crawl/fly away. So simply allow them to drop right into your soapy water trap! No touching needed.
- Insecticides can be used - just be careful to read the label for use on the plant you will be treating.
- Natural alternatives you can also use are Insecticidal soap or Neem oil-based insecticides to help control them directly. Or try this DIY!
- Inoculating Milky Spore into your lawn may help but it takes several years for it to become effective and is best done for smaller areas.
- Spreading Diatomaceous Earth into your lawn will help kill the grubs, but may harm beneficial insects like earthworms. Best for use in smaller areas and isn’t wildly effective.
- Inoculating your lawn with parasitic nematodes to help attack the grubs.
- A systemic insecticide can be used to protect your plants from the inside out. These are more effective than sprays because they won’t wash off, protecting the plants from the inside out!
- Treat your lawn for the grubs, stopping the cycle at the source. This is best treated from now until late September. But the timing of treatments is very important and you should contact your local County Extension Office to see when that is in your particular area.
- Stab them! Put on a pair of those funny spiked lawn-aerating shoe attachments and take a walk! The spikes are long enough to pierce the grubs when they’re actively feeding in the early spring. Focus on stomping around areas showing the most damage.
Treating the grubs in the grass areas eliminates the beetles from hatching and causing damage to some trees, shrubs and perennials! This stops the cycle of destruction and saves your plants from damage.
What are Japanese Beetles attracted to?
Besides being attracted to their favorite food, these beetles are also attracted to large collections of other Japanese Beetles! They send off pheromones to find a mate and attract many beetles in the process.
Japanese Beetles are also attracted to a wide variety of weeds such as Wild Grapes, wild Mallow and Smartweed, so keeping weeds and unwanted plants removed will limit how many of these pests you attract into your garden once they’re done destroying the more wild sources of food.
Traps and Lures
While there are lures and traps that use pheromones to attract them to their death, or the scent of flowers, these actually attract more of these destructive pests to your garden and invite them to feed on your plants. The traps work by catching many beetles, but not before attracting more beetles into your yard to lay eggs and eat your plants before falling victim to the traps.
Companion Planting & Trap Crops
One natural lure that also helps control the beetles is your garden variety of Geranium! Geranium plants have natural chemicals that once the beetles eat the blooms, which make them disorientated and unable to fly. You can simply sweep up the pests and dispose of them.
Garlic plants and their relatives, Rue and even Tansy herbs also deter these beetles. Anything highly aromatic such as Perennial and herbal Sage, Thyme and Parsley drive them away too. Hyssop, Yarrow, Lavender and anything in the Mint family repels them.
Planting these companions around more valuable plants helps lure them away from the prize.
Plant Damage
The damage to the plants actually causes the plants to release their own hormones and chemicals that, unfortunately, call more Japanese Beetles into the area! These chemicals can waft through the air for hundreds of meters. So removing the damaged leaves and flowers may stop the plant's response to the damage.
By keeping up with removing the beetles from your plants also reduces how much their own pheromones attract others to come and join the party.
Landscape Choices
If you live in an area or know of a certain plant that is more prevalent to damage, choosing a similar alternative when landscaping will help drastically.
Choosing a variety that is more resistant, or a different cultivar developed to not be as attractive to these pesky insects is another option.
Other Solutions
What is the natural enemy of the Japanese Beetle? Creatures that eat Japanese beetles in the adult form are spiders, assassin bugs, predatory stink bugs, and birds feeding their babies. However, even they can’t seem to keep up with how numerous these beetles are.
But unfortunately, the tasty grubs are also eaten by moles, voles, and skunks that tear up your lawn areas to get at the grubs in the roots of your lawn and cause more damage than the grubs will.
Barriers
Maybe you have that prized shrub or smaller plant that always gets damaged. One option is to cover it in fine netting during the worst of the Beetle season. This of course only works on smaller plants, but in some instances might just be able to save your prized blooms long enough for you to enjoy them!
For the vegetable garden, use row covers to completely protect long swaths of susceptible plants.
Stopping Them at the Source
Japanese Beetles are named such because they originated from a single island in Japan and were inadvertently brought to the US at the start of the 1900s.
By transporting some plant material as grubs in the soil of some plant roots brought over from the island. Here in the US, without a natural predator, they became a widespread nuisance in just a few years. By the 1920s, they were so prevalent that any efforts to stop them were halted.
Nature Hills uses Plant Sentry™ to ensure that all plant material that is grown in an area known for having these insects in the soil, or when these bugs are flying, will not be delivered into sensitive areas during that time they are active. Nature Hills is devoted to ensuring your native flora and fauna are protected.
Plant Sentry™ is a one-of-a-kind database that monitors and interprets the latest information in regulatory compliance for live plants. Their ever-vigilant eye helps hold growers accountable for following State and Federal regulations set out to help protect plants during the growing and shipping processes.
Gardening Without Worry!
Nature Hills Nursery is devoted to helping you have the biggest, best garden and the most beautiful landscape possible! Reach out any time for help from our horticultural staff and rest assured that we’ll be there for you every step of the way throughout your gardening adventure!
Happy Planting!
