One of the most distressful things for gardeners is when pests infiltrate their gardens. They savagely destroy vegetation that has been lovingly nurtured. It’s even worse when you don’t know how to get rid of them.
You may see some little critters crawling on your plants, but before you go into a panic, take a closer look. Not all bugs are bad and there are many insects that are beneficial.
Bugs such as ladybirds, spiders, parasitic wasps, and ground beetles are some of the good ones. They prey on pests and you should try to encourage their proliferation in your garden.
The problem arises when ‘not-so-friendly’ insects infest your plants. Even the smallest of these can cause havoc in your garden.
There are many different types of ‘bad bugs’, and one of the most common are the invasive Japanese beetles. Japanese beetles (Popillia japonica) were accidentally introduced to America where they quickly spread.
Due to natural predators in their native Japan, beetles of this species are not a problem. In the US, however, they are infamous for their destructive behavior.
If you are having trouble with this troublesome pest, keep reading to know how to get rid of them.
Understanding Japanese Beetles
Japanese beetles can show up in your garden at any time. Individually, they are quite harmless but the problem is that they feed in groups.
A single bug releases a ‘congregation pheromone’ when feeding. This is basically an invitation for other bugs to join the feeding frenzy.
A few bugs cannot cause much damage. when they congregate, however, you will notice significant damage to your garden.
So how do you know you have a Japanese beetle infestation?
What Japanese Beetles Look Like:
Japanese beetles are dubbed America’s number 1 turg-grass pest. Luckily, they are easy to spot compared to other pests. Here’s what to look for to identify Japanese beetles:
- They average half an inch in length.
- Mature beetles have copper-colored wing covers.
- The body is a greenish metallic color.
- The sides of the abdomen have five white patches of hair.
- The tip of the abdomen has two patches of white hair.
- Larvae have a brown head and a greyish-black lower section.
- A V-shaped pattern of hairs on the grubs’ last segment.
Japanese Beetle Life Cycle
Japanese beetles live above ground for two months of the year between July and September.
The Japanese beetle grubs spend most of their time underground. Unfortunately, when they mature, they can cause enormous amounts of havoc.
In these two months in early summer, females regularly burrow into the turf and lay 40 – 60 eggs.
When these eggs hatch, the larvae feed on grassroots before hibernating during winter. They will stay inactive until early spring before turning into pupae.
The pupae turn into adults and proceed to feast on your plants.
When To Look For Japanese Beetles:
The typical feeding period for Japanese beetles begins in mid-May to early June in the Southern States. As it gets warmer in the Northern states, they usually appear in mid-June.
Look for beetles on warm sunny days especially on plans with direct sunlight.
They are most active on warm days when temperatures reach above 21°C.
You will usually find them feeding between 9 am and 3 pm.
Symptoms of Japanese Beetle Plant Damage
Adult beetles ‘skeletonize’ leaves by eating between leaf veins, leaving holes behind. This causes the leaves to quickly wither and die.
They also consume flowering buds and fruits, especially those that are overripe.
The grub can kill seedlings but mostly prefer turf, making it feel spongy and easy to pull off. The grass will appear dehydrated with random brownish patches.
Where are Japanese Beetles Found?
Japanese beetles are native to Japan and were first detected in the U.S in 1916 in New Jersey. Since then, they have spread to most states east of the Mississippi River and some western states.
Due to their destructive nature, there are Japanese Beetle Quarantine and Regulations to stem the spread from Eastern states.
If you live in these states, your garden could be at risk, so keen gardeners are advised to keep an eye on their yards.
What Do Plants Do Japanese Beetles Eat?
These insects feed on the flowers, fruit, foliage of over 300 plant species. They especially like plants such as:
- American linden
- Japanese maple
- Norway maple
- Cherry, peach, plum & apricot trees
If you live in an area with regular infestations, avoid planting these varieties. This will work to protect your other plants.
They generally avoid eating some plants unless there are limited food sources. Some of these include:
- Red and Silver Maple
You can reduce the rate of infestation by including them in your garden.
Once the beetles finish feeding, they leave an odor that then attracts more beetles to that area. Regular trimming of affected plants will reduce further infestations.
As larvae, they feed on roots which indicates you have a larvae problem underground.
Top Tip: Japanese beetles also eat geraniums. Geraniums however make them temporarily paralyzed. You can use geraniums as trap plants when picking off Japanese beetles.
Tips to Getting Rid of Japanese Beetles
Although they can cause a significant amount of damage, Japanese beetles can be controlled.
It’s important to control both flying insects and grubs in the soil. If you do one without the other, you are essentially only treating half the problem.
Beetles can also fly up to 5km in search of food so once an infestation occurs, the best you can do is control the damage.
Here are a few tips on how to get rid of Japanese beetles:
- Plant Modification
Take a look at the plants above to see those that are likely to attract Japanese beetles. Whenever possible, replace them in areas prone to infestation of Japanese beetles.
If you really cannot replace your beloved roses or other plants prone to infestation, spread them out within your garden. Place them alongside plants that they find distasteful.
Take care of your plant foliage as damaged plants also attract Japanese beetles.
- Bacterial Milky Disease
Also known as a milky spore, this is a fungal disease that targets only the Japanese beetle grubs. This is not a quick fix as it takes 2-3 years for the spore count to build up.
The good news is, once established, this method works for years. Although expensive, it might be your best bet if you are looking for a long-term solution.
- Beneficial Nematodes
Nematodes containing strains Heterorhabditis spp and Steinernema have been shown to be get rid of up to 95% of Japanese beetle spores. The latter is also known to reproduce in the cadaver of the dead beetle and populate the area around it. Using both strains maximizes the benefits of this method.
Experts advise you to apply the nematodes in early October as the grubs are actively moving. This makes them easy targets for the nematodes.
It is recommended to apply the nematodes in the evening with 23000 nematodes per square foot.
Irrigate the site before and after application. This will allow them to enter the moist soil underneath. Providing sufficient water will increase their effectiveness and aid in reproduction.
It may sound tedious, but this may be the most effective way to get rid of Japanese beetles from shrubs and flowers.
Just walk through your garden with a bucket of soapy water and pick each beetle off the leaves. Drop them in the soapy water to kills them.
Do not pour the water back onto your law as beetle larvae may still hatch from the dead female beetles.
- Row covers
If you want complete protection, place row covers on the plants most susceptible to infestation.
You should keep them on during the 6-8 week feeding period for adequate protection.
These however will not work on plants that need to be pollinated by other insects.
- Drop cloths
This method can greatly reduce the number of mature beetles if used consistently.
Lay a large cloth over your plants early in the morning where the beetles will congregate. Simply collect them and drop them into a bucket of soapy water.
You can also put cloth beneath the plants and shake the beetles on to the cloth.
You can buy Japanese beetle traps from most garden supply stores, or just make your own. The beetles are attracted to the smell of fermenting plant material.
Simply place a can of fruit cocktail in the sun for about a week to let it ferment. Place in a light-colored bucket, on top of bricks so it reaches the top of the bucket.
Fill the bucket with water just to the top of the can. The beetles will fly towards the bait and likely fall and drown in the water.
Be careful when using bait as they are known to attract many beetles. As they move towards the trap, some of them inadvertently land on nearby vegetation.
Sometimes, baits cause even more harm than good. If you do resort to using baits, place then as far from your glorious plants as possible.
The active ingredients in neem oil interfere with the insects’ urge to eat, mate, or lay eggs.
Neem oil is also an antifeedant meaning it makes your plants unattractive to pests. Over time, the population will decrease.
It is not a quick fix but is effective when used early in the infestation period.
Even better, use it on your plants even before the first beetles land in your garden.
To make 4 gallons of your own neem oil mixture, follow these easy steps:
- Mix 4 gallons of warm water with 5 teaspoons of insecticidal soap.
- Slowly add 6.5 oz neem oil while stirring constantly.
- Pour into a spray bottle.
- Shake the spray well before usage.
Use within 8 hours and spray the neem oil solution generously on plant foliage and the soil around.
Make sure to spray on the underside of leaves but avoid plant blossoms. Do this once a week, and re-spray after rain.
The bugs will not die immediately unless directly sprayed. Those that ingest the coated leaves will eventually die.
- Soapy Water
Mix 2 tablespoons of liquid soap mixed with 1 gallon of water to spray your lawns. This causes the grubs to surface making them vulnerable to birds and other predators.
Use this spray one a week until there are no more grubs coming to the surface.
- Homemade Insecticide
Instead of immediately opting for store-bought insecticides, why not try this homemade solution? Mix 1 teaspoon of dishwashing soap with 1 cup vegetable oil and shake well. Add 1 quart of water and 1 cup of rubbing alcohol and shake vigorously.
Spray the mixture sparingly onto affected plants every ten-days. It is advised to try it on a small part of the plant and check for any adverse reaction within 24 hours.
Only spray in the cool, morning hours and never during full sunlight. If you notice that plants are wilting, rinse off the solution with clean water.
Pesticides are an option, especially if you are not growing edible plants. You do need to be careful to not deter pollinators from your plants.
Products such as Sevin can reduce the pests in your garden. Check out this video for how to use it.
Protect and make your garden pest-free
You may have a Japanese beetle infestation or many other kinds of bad bugs.
Take a look at expert advice on how to get rid of pests.