If you’ve noticed skeletonized leaves on your prized shrubs, you might be wondering: do Japanese beetles eat hydrangeas? Unfortunately, the answer is a resounding yes. These invasive pests are not picky eaters and hydrangeas are often on their menu. Seeing your garden under attack can be frustrating, but understanding their behavior is the first step to protecting your plants.
This guide will help you identify the damage, explain why these beetles are such a problem, and give you a clear plan to control them. We’ll cover everything from immediate actions to long-term prevention.
Do Japanese Beetles Eat Hydrangeas
Japanese beetles (Popillia japonica) absolutely feed on hydrangeas. While they have favorite plants like roses and grapes, hydrangeas are a common target when beetle populations are high. They are especially drawn to varieties with thinner, more tender leaves. You’ll often find them clustered together, feeding in the warm sun on the upper parts of the plant.
The damage is very distinctive. They don’t eat the entire leaf. Instead, they chew the tissue between the leaf veins, creating a lace-like or skeletonized appearance. This weakens the plant, reduces its ability to photosynthesize, and can lead to a loss of blooms if the infestation is severe.
Identifying Japanese Beetle Damage on Hydrangeas
It’s important to confirm you’re dealing with Japanese beetles and not another pest. Here’s what to look for:
* Skeletonized Leaves: This is the classic sign. The leaf veins remain intact while the green tissue between them is completely eaten away.
* Clustered Feeding: You will rarely see just one beetle. They feed in groups, so you’ll often spot several to dozens on a single flower head or leaf cluster.
* Bronze or Brown Patches: As the damaged leaf tissue dies, it turns brown, making the damage even more noticeable.
* The Beetles Themselves: Adult Japanese beetles are easy to identify. They are about 1/2 inch long with a metallic green head and coppery-brown wing covers. They have small white tufts of hair along the sides of their abdomen.
Why Are Japanese Beetles So Destructive?
These beetles are a double threat. The adults you see munching on leaves are only part of the problem. Their life cycle continues underground, where their larvae, called grubs, cause separate damage to your lawn.
* Adult Stage (Above Ground): They emerge from the soil in early to mid-summer, usually around June or July, depending on your climate. Adults live for about 30-45 days, during which they feed and mate.
* Grub Stage (Below Ground): Females lay eggs in your lawn. These eggs hatch into white, C-shaped grubs that feed on grass roots. This can cause brown, dead patches in your turf that peel back easily.
* No Natural Predators: In their native Japan, natural controls keep them in check. In North America, they have few effective predators, allowing their populations to grow rapidly.
Immediate Actions: How to Get Rid of Beetles on Hydrangeas
When you spot an active infestation, you need to act quickly to minimize damage. Here are the most effective direct control methods.
1. Hand-Picking (Most Immediate Solution)
This is surprisingly effective, especially in the early morning or late evening when the beetles are sluggish.
1. Fill a bucket with soapy water.
2. Hold the bucket underneath the cluster of beetles.
3. Gently tap the leaf or stem. The beetles will fall off into the soapy water and drown.
4. Dispose of the water away from your garden. Do this daily to break their breeding cycle.
2. Neem Oil and Insecticidal Soaps
These are organic options that can help deter feeding.
* Neem Oil: This acts as both a repellent and an insect growth regulator. It’s most effective when applied in the evening to avoid harming beneficial insects and to give it time to work before the sun breaks it down. It needs to be reapplied after rain.
* Insecticidal Soap: This can kill beetles on contact by breaking down their outer shell. Spray it directly on the beetles. It has no residual effect, so you must hit the pests directly.
3. Targeted Chemical Insecticides
For severe infestations, you may consider a last-resort insecticide. Always choose products labeled for use on Japanese beetles on ornamental shrubs like hydrangeas.
* Look for active ingredients like carbaryl or cyfluthrin.
* Apply in the evening when bees are less active.
* Follow the label instructions precisely for mixing and safety.
Long-Term Prevention and Control Strategies
Stopping the cycle is key to lasting control. This means targeting both the adults and the grubs.
Grub Control in Your Lawn
Reducing the grub population in your lawn means fewer beetles next summer.
* Beneficial Nematodes: These are microscopic worms you apply to your lawn (in late summer or early fall). They seek out and kill grubs naturally.
* Milky Spore: This is a bacteria that specifically targets Japanese beetle grubs. It takes a few years to establish in your soil but provides long-term control.
* Grub-Specific Insecticides: Apply these in late summer when young grubs are actively feeding near the soil surface.
Protecting Your Hydrangeas
* Physical Barriers: Use fine mesh netting or floating row covers over your most precious hydrangeas during peak beetle season (June-August). This physically prevents them from reaching the leaves.
Trap Plants: Plant something they prefer more than hydrangeas, like roses or grapevines, away from your main garden. The idea is to lure them away, but this can backfire if not placed correctly—keep traps at least 30 feet away from plants you want to protect.
Avoid Japanese Beetle Traps: Commercially available pheromone traps are not recommended. They attract beetles from a wide area and often end up bringing more into your yard than they catch, leading to worse damage.
Choosing Resistant Hydrangea Varieties
While no hydrangea is completely immune, some varieties seem to be less appealing to Japanese beetles, possibly due to thicker or rougher leaf textures. Consider these types if you live in a high-population area:
Oakleaf Hydrangea (Hydrangea quercifolia): Its large, textured leaves are less favored.
Climbing Hydrangea (Hydrangea petiolaris): Often experiences less damage.
Rough-leaf Hydrangeas: Varieties like Hydrangea aspera have a hairy leaf surface that beetles tend to avoid.
Smooth hydrangeas (Hydrangea arborescens) and panicle hydrangeas (Hydrangea paniculata) often fare better than the bigleaf (Hydrangea macrophylla) types, which can be more susceptible.
FAQ: Common Questions About Beetles and Hydrangeas
Q: Will my hydrangeas recover from Japanese beetle damage?
A: Yes, in most cases. Hydrangeas are resilient. While the damaged leaves will not repair themselves, the plant will usually produce new leaves later in the season. Consistent feeding over several years is more harmful than one season’s damage.
Q: What other plants do Japanese beetles eat?
A: They have over 300 host plants. Their favorites include roses, grapes, linden trees, raspberries, and marigolds. They also enjoy beans, peaches, and many other ornamental plants.
Q: When is Japanese beetle season?
A: Adult beetles are most active for about 4-6 weeks in the summer, typically from late June through August. The timing depends on your local climate and weather conditions for that year.
Q: Are there any natural predators I can encourage?
A: Some birds (like starlings and grackles) will eat grubs, and animals like skunks and raccoons will dig for them (which causes its own lawn damage). Tachinid flies and some wasps parasitize the adults, but they are not numerous enough to control a large infestation on there own.
Protecting your hydrangeas from Japanese beetles requires a combined approach. Start by removing beetles by hand as soon as you see them. Focus on breaking their life cycle by treating your lawn for grubs in the fall. Consider protective netting during peak season and choose less-susceptible varieties for new plantings. With persistence and the right tactics, you can enjoy your beautiful hydrangeas with minimal damage from these voracious garden pests.