Japanese beetles are slow and clumsy, so it is quite effective to pick them off your plants or to spray them with a soap and water solution. You can simply smash them with your palm or foot when they fall.
Geraniums may help deter Japanese Beetles
Unbelievably, geraniums were shown to be a natural deterrent for adult beetles in 1929. The geranium flowers and leaves that the beetles consume put them into a narcotic state for 12 to 18 hours. They like lying on their backs while in this transformed state, which makes them vulnerable to predators and simple to collect and crush by gardeners. Some bugs consume the delicious geranium leaves so frequently that it causes their demise.
However, do not interplant geraniums around your roses in the hopes that doing so will keep pests away. Interplanting will have the reverse effect and attract so many Japanese Beetles that your roses will become afflicted because of how much they adore geraniums. The narcotic compound in geranium leaves is thought to be amplified by the sun, so grow a patch of geraniums far away from the plants you want to protect.
Geraniums: do they deter Japanese beetles?
Scientists with the Agricultural Research Service believe that geraniums may hold the answer to stopping the destructive Japanese beetle, which consumes almost 300 plant species and causes $450 million in damage to the decorative plant sector each year (ARS).
Popillia japonica Newman, the insect, may gorge itself on a wide range of plants, including ornamentals, soy, maize, fruits, and vegetables. However, the beetle turns over onto its back, its legs and antennae begin to gently twitch, and it becomes paralyzed after only 30 minutes of devouring geranium petals. When paralyzed in a laboratory setting, the beetles usually recover within 24 hours, but in the wild, they frequently perish after being discovered and eaten by predators.
Chris Ranger, an entomologist with the ARS, is trying to find a way to use geraniums to keep the beetles under control at the agency’s Application Technology Research Unit in Wooster, Ohio.
One of the leading producers of horticultural plants, the most of which are cultivated in greenhouses, is Ohio, which borders Michigan. Susan Stieve, curator of the Ornamental Plant Germplasm Center at Ohio State University in Columbus, Ohio, is involved in additional research that will help the horticultural sector.
To determine whether a particular breed of begonias can withstand cooler temperatures, Stieve is working with OSU collaborators and horticulture Jonathan Frantz of the ARS Greenhouse Production Research Group in Toledo, Ohio.
The begonias are being examined at two production temperatures that are five and ten degrees Fahrenheit lower than usual, respectively. Secular hints that can be utilized to find prospective germplasm can be found in the naturally occurring begonias, which can be found in a wide range of climates and elevations. For farmers of ornamental plants in colder areas, the ability to grow begonias at lower temperatures could result in lower greenhouse heating costs.
ARS is the main intramural scientific research organization for the U.S. Department of Agriculture.
What kind of plant repels Japanese beetles?
- As long as the adult beetles are actively eating, hand picking them out can be the most efficient technique to gain control, although it does take daily attention, frequently for weeks. Early in the morning is excellent because that is when they are at their most sluggish. Shake the afflicted plants on a drop cloth to get rid of the beetles. The beetles should be collected and placed in a bucket of soapy water. Dead insects and damaged leaves should be removed because they can attract new beetles.
- Japanese beetle traps: The outcomes of this technique can be unpredictable. The beetle traps are effective at trapping the insects that crawl into them, but their bait may end up luring more beetles from the surrounding surroundings, doing more harm than good. They should be kept well away from any plants that beetles might damage, if they are to be employed.
- Neem oil: Neem oil lowers insect feeding when used as a natural pesticide. It works best when used as soon as damage is noticed. Honeybees and other beneficial insects are safe around neem oil. Contact your regional cooperative extension services for a list of alternative insecticides that are legal to use in your area.
- Put up a wall: Over ground crops throughout the 6- to 8-week feeding cycle, use row covers.
- Planting sacrifice crops of favored plants far from desirable crops can serve as a trap to entice adult insects. To prevent the beetles on these sacrifice crops from becoming a greater issue, you will still need to trap or kill them.
- Avoid sensitive plants including roses, grapes, beans, raspberries, rose of Sharon, apples, crabapples, cherries, mountain ash, birch, American & English elm, linden, crape myrtle, and pin oak if you live in an area where Japanese beetles are a common problem. Use them sparingly and scatter them over your landscape, at the absolute least, to avoid setting up a single enormous buffet table.
- Plants that are resistant to pests should be used in place of vulnerable varieties, such as boxwood, dogwood, hemlock, holly, magnolia, red and silver maples, oaks, sweet gum, tulip trees, euonymus, and common lilac.
- Companion planting can help keep Japanese beetles away from susceptible plants by incorporating plants that repel them, such as catnip, chives, garlic, unscented marigolds, nasturtium, white geranium, rue, or tansy.
Japanese insects are killed by what flower?
Put your geraniums in full light to increase the toxicity of the geraniol oil in geraniums, as reported by Michigan State University. After feeding on the geraniums, Japanese beetles often drop off the plant and die within eight to twelve hours. Daily collect the dead Japanese beetles and discard them.
- The leaves, roots, and fruits of various North American plants, lawns, shrubs, and trees have been severely harmed by the Japanese beetle (Popillia japonica Newman), which was introduced to the United States from Japan in 1916.
- According to Michigan State University, the majority of Japanese beetles get paralyzed and many of them pass away after consuming geranium foliage and flowers.
4 cups of water should be added to a small pan. Using a spoon or your hands, combine 1/2 cup of dish soap into the water. While not bubbling, the water should appear soapy.
Hold the pan of soapy water under the geranium in the early morning, when Japanese beetles tend to be lethargic and less likely to run. Shake the plant’s leaves gently to let the beetles land in the pan. They won’t be able to crawl out of the pan because of the soap, and they’ll drown.
If the infestation is severe, spray a pyrethrum-based pesticide on the geranium plant. Use the pesticide every three or four days to control Japanese beetles. Follow the instructions on the label for application.
- 4 cups of water should be added to a small pan.
- The pesticide should be applied every three to four days to manage Japanese beetles.
If you have rosebushes or other plants that are extremely vulnerable to Japanese beetle damage, think about putting geraniums nearby. Geraniums can help control Japanese beetles and keep them away from other plants because, according to the University of Kentucky, they frequently prefer eating them to other plants. Geraniums are regarded as the best “trap crop” for securing other plants vulnerable to infestation by the Japanese beetle.
What keeps Japanese bugs away naturally?
Iridescent green Japanese beetles (Popillia japonica) pose a serious hazard since they devour a wide range of plants. Because of the lacy skeleton that their leaf gnawing leaves behind, you can frequently see where the damage was.
What Are Japanese Beetles?
When it comes to the plants that these tiny insects eat, they are not picky, but they do have favorites (like roses). In fact, hundreds of different species consider them to be a pest. They are one of the most destructive insect pests to crops in the Eastern and Midwestern regions of the United States.
The Japanese beetle was isolated by water and kept in control by its natural predators exclusively on the islands of Japan before it was accidentally introduced to the United States in the early 1900s. A regulation that forbade the importation of plants with soil roots was passed in 1912. Unfortunately, the Japanese beetle was able to invade this nation because the law wasn’t immediately put into effect.
The majority of entomologists concur that the beetles arrived as grubs in the soil on Japanese iris roots. The first coppery-winged pests were discovered in a nursery close to Riverton, New Jersey, in 1916. By 1920, eradication operations had been abandoned because the beetle had grown too numerous and pervasive.
How to Identify Japanese Beetles
Japanese beetles have heads that are half an inch long and shiny blue-green in color. Their wings are brown, and the sides of their abdomen are lined with tiny white hairs. Their backs are copper in color. Typically, Japanese beetles forage in tiny groups.
They are 1-inch-long, white, c-shaped grubs that feed on the roots of numerous plants before transforming into adult beetles in June. These grubs frequently cause problems in lawns.
They don’t live long after becoming adults, but they are voracious. The reason for the extensive damage is because they attack plants in groups. The adult Japanese beetle has a short life cycle of only 40 days, but it can travel great distances. Even if you are successful in reducing your population of Japanese beetles, they could still invade your property from your neighbor.
Ohio State University provided the image. Leaves that have been attacked by Japanese beetles seem skeletal.
Signs of Japanese Beetle Damage
The adult Japanese beetles target more than 300 different species of plants, however when it comes to garden plants, they are most frequently found on roses, as well as beans, grapes, and raspberries. What to watch out for includes:
Skeletonized Leaves and Flowers
Japanese beetles leave behind a lacy skeleton after chewing leaf tissue from in between the veins. You’ll immediately recognize “skeletonized” leaves when you see them (i.e., only have veins remaining). Be sure to recognize the beetle by its appearance as well (although Mexican Bean Beetles can also leave leaves skeletonized).
Japanese beetles are typically found next to damaged leaves, so carefully examine the plant. Watch the ground beneath the plant as well; if it is disturbed, the beetles may drop off the plant in response.
Unhealthy, Brown Patches in Lawn
When Japanese beetle grubs overwinter in the soil, they harm grass because they eat the roots of garden plants and lawn grasses. As a result, the lawn may develop brown patches of dead or dying grass that are simple to pick up due to the weakened roots.
How to Get Rid of Japanese Beetles
Fortunately, using excellent horticultural techniques like watering and fertilizing will lessen the harm that these beetles cause, but sometimes you just have to get rid of them. Here are a few concepts:
- Hand Pick: Because they are so visible, Japanese beetles are quite simple to knock into a can of soapy water. Yes, it takes a lot of time, but it’s the best way to get rid of these pests. Just be careful. Once you have picked them off, drown them in a solution of water and 1 spoonful of liquid dishwashing soap.
- Spraying plants with neem oil prevents adult beetles from eating on them as well. Neem oil and potassium bicarbonate sprays can be somewhat useful, especially on roses. Neem oil contains a chemical that the adult beetles consume and transfer to their eggs, whereupon the young larvae perish before becoming adults. Note: Avoid using neem close to bodies of water like lakes, rivers, and ponds because it might kill fish and other aquatic life. After rain, it must be reapplied.
- Row Covers: Use row covers to protect your plants against Japanese beetles during their 6- to 8-week feeding cycle, which starts in the southern United States in mid- to late May and in the North in mid- to late June. Row coverings will keep pests out, but they will also keep pollinators out, so if your crops require pollination, make sure to take them off.
- Use a Dropcloth: Spread out a dropcloth, and in the early hours of the day when the beetles are most active, shake the beetles off and pour them into a pail of soapy water.
- Pesticides: Ask your neighborhood cooperative extension or garden center about insecticides that are legal to use in your area before you decide to spray or dust with them.
- Alternately, try this improvised fix: Add 1 quart of water to the mixture of 1 teaspoon liquid dishwashing detergent, 1 cup of vegetable oil, and a good shake. To emulsify, add 1 cup of rubbing alcohol and shake ferociously. Use this mixture on pests every ten days by pouring it into a spray bottle. Be cautious and use homemade sprays sparingly as there is a greater chance that they will harm plant leaves. Always test your spray on a small area of your plant, wait 24 hours to check if there are any bad responses, and then continue to spray the rest of the plant if there are none.
- Sprays should only be used in the morning and never when it is hotter than 90 degrees. If your plants begin to wilt, immediately rinse the leaves with fresh water.
- Japanese beetle traps: Yellow target traps baited with a pheromone attractant effectively manage big populations of insects, but occasionally draw in too many of them. Place one far from your garden to avoid attracting bugs from all over the city and creating a bigger problem. To avoid the beetles landing on your favorite flowers and crops while en route to the traps, if you decide to try them, place the traps far from the target plants.
- Fruit Cocktail Trap: There are many different types of Japanese beetle traps available for purchase, but the most are no more effective than a can of fruit cocktail. The can should be opened and allowed to ferment for a week in the sun. After that, put it in a light-colored pail on top of bricks or wood blocks and fill it with water until it is just below the can’s top. The pail should be positioned around 25 feet away from the plants you want to protect. In pursuit of the tasty bait, the beetles will plunge into the water and perish. Restart if rain washes the bait away.
- For grub control in lawns and garden beds, use parasitic nematodes.
- Geraniums should be planted close since Japanese beetles are drawn to them in particular. They consume the blossoms, quickly become lightheaded due to the geranium’s natural compounds, fall off the plant, and then you can easily dispose of them with a dustpan and brush. To protect more priceless plants from the ravages of Japanese beetles, place geraniums close by.
- Note that insecticides won’t completely protect roses because they expand too quickly and are particularly alluring to beetles. Instead, clip rose buds and spray rose bushes. Nip the buds and spray the plants to protect the leaves when rose bugs are most prevalent. Allow the shrubs to bloom after the insects start to disappear. Application timeliness and thoroughness are crucial. Before damage is done, start treatment as soon as beetles arrive.
For further advice on rose maintenance for rose growers, visit our Growing Guide for Roses!
Jeff Hahn, University of Minnesota, provided the image. Picking Japanese beetles off the plants before they cause too much damage is occasionally the simplest method to get rid of them.
How to Prevent Japanese Beetles
Unfortunately, there is no magic elixir that can make this bug disappear. Keep your landscape healthy as a general preventive maintenance strategy, according to experts. Eliminate unhealthy, diseased trees as well as any fruit that is ripening too soon or has a disease that may draw Japanese beetles. Try the following advice:
- The Best Plants to Choose: Pick plants that Japanese beetles won’t be drawn to. The Best and Worst Plants for Japanese Beetles are listed on our website. It can also be beneficial to spread out their favorite plants rather than concentrating them in one area of the yard.
- Get Rid of Grubs: Spray the grass with 2 teaspoons of liquid dishwashing detergent diluted in 1 gallon of water per 1,000 square feet during the grub stage in late spring and fall (beetles have two life cycles per season). Grubs will come to the surface, and birds will adore you. Until there are no longer any grubs, spray once every week.
- Milky Spore: To reduce the number of Japanese beetle larvae, you can spread the fungus milky spore on your grass. As they consume food in the soil, the grubs consume the spores. For this strategy to work, the spore count needs to be present for two to three years. Fortunately, the spores can survive for many years in the soil. Since all the soil within five-eights of a mile needs to be treated for effective control, this treatment is expensive.
- Beneficial Nematodes: To control the larvae, you can also spray sod in parasitic nematodes. When the grubs are young and if the lawn is watered both before and after application, the nematodes must be used. The most effective preparations appear to comprise the Heterorhabditis species.
- Companion Plants: Planting companion plants might be an effective pest-reduction method. To keep Japanese beetles away from your damaged plants, try putting garlic, rue, or tansy nearby. (The idiom “Roses adore garlic” is common.) All types of aromatic plants and herbs make excellent companions. Japanese beetles and aphids may both be deterred by scented geraniums (Pelargonium), rue (Ruta), feverfew (Tanacetum), parsley (Petroselinum), and thyme (Thymus). Try the following herbs: catmint (Nepeta), calamint (Mentha), Russian sage (Perovskia), yarrow (Achillea), oregano (Origanum), ornamental and culinary sage (Salvia), anise-hyssop (Agastache), and agastache (Calamintha). According to legend, four o’clocks (Mirabilis) and larkspur (Delphinium) serve as decoys by luring Japanese beetles who love roses to consume their lethal leaves.
- Tiphia vernalis or T. popilliavora, two natural species of parasitic wasps and flies that prey on beetles and can be beneficial insects, can be attracted to your garden. Although they are likely to attack the larvae, they are not very efficient at lowering the beetle population as a whole.
WARNING: Honeybees, native bees, and other pollinators are particularly poisonous to many dusts or sprays. If these substances need to be applied to plants during the bloom period, do not do it when bees are visiting the blooms (late morning through mid-day). You might need to get in touch with local beekeepers in advance if you plan to treat more than a few garden and yard plants so that they can safeguard their colonies.