11 Common Hydrangea Pests: How to Prevent and Treat Them

In the summertime, hydrangeas are covered in large blossoms that will fill any gardener with happiness and pride. Just when you think things are going great you notice a plant that is just looking…off. Hydrangeas are strong and resilient plants but unfortunately even they can become victims of your garden pests.

So what happens when you notice pests on your hydrangeas? While prevention is always the best method of keeping these prolific bloomers healthy, you can treat pest infestations in hydrangeas. They share common pests with many different garden plants, and have a few that tend to like them more than others.

Not checking routinely for pests is one of the most common mistakes hydrangea gardeners make. Don’t fall into that trap! Follow along, and we will take a look at eleven pests that you may find on your hydrangea and how to choose the best way to get rid of them!

Hydrangea Pests

You would be hard pressed to find a garden that is pest free. Pests usually found on hydrangeas are, for the most part, pretty common garden pests. Use this guide to identify the pests you may be finding among your summer beauties, or simply to learn how to treat them and if possible, prevent them.

Aphids

Aphids can be found in almost every garden on any plant, and hydrangeas are no exception. Aphid feeding causes yellowing of the leaves and stems, however, aphids are also responsible for transmitting diseases from plant to plant.

While many garden pests can be easily controlled by natural predators, such as bats or birds, aphids use their waste that is high in sugar to attract ants. Ants do not harm plants, however they can protect the aphids from predators.

Aphids are small pear shaped insects that are typically green but can also be yellow, brown or black. They have long antennae and typically travel in large populations. They like to hang out on the underside of leaves.

Aphids can be hard to notice since they are so close in color to plant stems, but if you notice yellowing with no bugs in sight just flip over the leaves and look for these tiny insects. If you notice a larger than normal population of ants near your plant, you may want to take a closer look to see if the ants are hiding aphids.

The best way to prevent aphids in your garden is to keep it clear of any leaf litter or weeds. Removal of nearby infected plants will help to prevent high populations of aphids from appearing. To control an infestation of aphids you could try brushing them off with your hand, spraying the plant down with a hose, or using an insecticidal soap.

Black Vine Weevil

The bulk of injury your hydrangea could endure from this insect is by the larvae feasting on the roots of the plant. The grubs of these beetles will start first by eating away at the small feeder roots, and will quickly move on to the larger woodier roots.

The damage done to these larger roots is what could be the end of your hydrangea plant. The plants will begin to yellow from the top down, slowly turning brown and eventually dying. You may also spot the black adults nibbling on your leaves as they get ready to lay their eggs.

For prevention, make sure to pull any mulch or hiding places back from the base of your hydrangeas where you can. You’ll need to make sure you weed regularly, and you can also encourage natural predators.

These insects can really cause damage in your landscaped areas and once found are best treated with pesticide. Because grubs cause the bulk of this damage you will want to treat them as well using a granular pesticide. Remember, it’s important to not use pesticides until after your flowers are in bloom in order to keep pollinators safe!

Deer

Hydrangeas are not the favorite food of deer and they will most likely leave the leaves alone. However, when times get tough deer will munch on the leaves, as well as the flower buds (Gasp!).

It is easy enough to spot deer damage: all you need to do is take a look at the leaves. Deer pull on the leaves and leave a torn appearance to them.

Deer prevention is the best route here. You can either use a black deer net that will protect your leaf and flower buds. Or you can use a deer repellant that will give your plants a foul odor and taste.

Four lined plant bug

These bugs live most of the stages of their lives in the plant tissues of many of your garden plants, hydrangeas included. Once the tiny nymphs hatch they hang out and feed on the leaves, leaving very little noticeable damage to your plant.

As the insects age the damage becomes more pronounced and more distinct. These insects leave small pockmarks all over their feeding area. These pockmarks will look like small brown circles that typically appear in a cluster. Lucky for us gardeners the adults-only feed for about a month and the damage they cause is aesthetic.

If you notice this pockmark damage simply pinch off the leaves, promoting new growth! Insecticidal soap or neem is the most effective form of both prevention and control.

Leaftiers

Hydrangea leaftiers are a species of moth that are brown and white in color. They will lay their eggs on the branches.  When the caterpillars emerge they use their silk to web together a few leaves and they will begin feeding on those leaves.

These webbed leaves will be fairly obvious, and if you have an infestation there will be many of these leaf sacs on your plant causing the plant to become less aesthetically pleasing than you were likely hoping for.

Winter and spring hydrangea care are essential for management of this pest. If you clean up lower formed stems before spring, this can help prevent these pests from climbing on your plant.

If you notice damaged and webbed leaves, you can gently pull the leaves apart and remove the caterpillar by hand. When the caterpillars are ready to pupate they will fall to the soil and carry out their life in the dirt. Keeping your garden neat will remove any of the pupating caterpillars.

Japanese Beetle

If you spend a lot of time in the garden you may be familiar with Japanese beetles. Japanese beetles are another very common garden pest. They are not too picky when it comes to their meal choices. They tend to be a common problem on oakleaf hydrangeas, but not typically on the other hydrangea species.

The adult Japanese beetles are what cause the most plant damage. They have copper-colored backs with a metallic blue or green head. Japanese beetles nibble at the leaves of plants leaving just the veins behind leading to a lacy looking leaf.

The best way to prevent adult Japanese beetles is by controlling them when they are in their larval state as grubs which can be tricky. These grubs can typically be found in your lawn, or in your gardens nibbling on roots. Sometimes you can find grub trails in the lawn. These typically look like streaks of dead grass.

If you don’t notice that you have a Japanese beetle problem until the adults have presented themselves, don’t worry, there are easy ways to manage these insects. Bonide carries a Japanese beetle killer that is available at most garden centers.

It is important not to use pesticides while the hydrangeas are blooming to keep pollinators safe. If you don’t want to use pesticides at all, fill up a bucket of soapy water and knock the beetles into the bucket using your hand.

Nematodes

You may be familiar with beneficial nematodes but there are also some bad guys in this group of roundworms. These nematodes will nibble away at the roots causing small galls, or swelling, on the roots of the plants.

Unlike some underground eaters, the symptoms of nematodes feeding are easily detectable above ground. The plant will have unexplained yellowing and wilting in the summertime. It might trick you into thinking your hydrangeas need to be watered. If you do try watering to revive the plants with little success nematodes could be the cause.

The best source of prevention for nematodes is ensuring your soil isn’t too moist. You will also need to make sure pruning shears are clean and sterilized after hydrangea pruning. Nematodes can be transmitted through dirty tools, and you don’t want to transmit nematodes from plant to plant.

Nematode control is available at garden centers and is the best source of control for these nearly invisible problem makers.

Rose Chafer

Rose chafers sometimes feed on hydrangea.  Adult rose chafer beetles are green or tan beetles that are about one-third of an inch in length with long legs. They are most often found in large numbers where soils are sandy.

Hydrangeas do best in well-draining soils that are rich in compost. This is also an environment where the rose chafer doesn’t thrive. The grubs found in the soil may damage the roots, whereas the beetles will leave your leaves looking similar to the way a Japanese beetle does.

If you use topsoil in your garden, you may want to reconsider, or thin it out. Rose chafers lay eggs in topsoil, so this is your best method of prevention. They are also likelier to attack sun friendly hydrangea varieties, since they prefer sunnier spots to lay their eggs.

Hand removing the beetles and knocking them into a bucket of soapy water will help temporarily remove these insects, however, because these are flying bugs new beetles may appear every day. It may be a better option to treat for the grub stage with a granular grub killer.

Scale

Hydrangea scale is a garden pest that feasts on the underside of the leaves as well as the branches. Scale sucks the sap from the plant, causing the plant to suffer and weaken, resulting in less vigor.

The nymph and adult stages of scale are very small and yellow, and may be hard to see with the naked eye. You will most likely notice white oval shaped eggs attached to the stems of your hydrangeas if you have a scale infestation.  The symptoms of these insects may be hard to notice, and likely won’t kill your plant.

Prevention of these insects can be difficult, however, removal by hand is a good option. This may take a lot of time and you may opt to use pesticides in the summer instead.

Slugs

Slugs typically attack younger hydrangea foliage. They prefer to munch on decaying foliage so keeping your gardens clear of litter is very important. You may notice slug damage by spotting some ragged edged leaves, and holes in the leaves. You may also notice the large bugs themselves, or the slimy path they leave behind.

Slugs like to hang out in dark damp areas. Keeping the garden clear of plant debris is a good start. Keeping the leaves dry by watering only the base of the plant will limit hiding places for slugs as well. Copper tape deters slugs, you can also use other copper gardening decor. Spraying soapy water on the leaves can also help get

Removing slugs by hand is very effective, as is using slug killer, or plants that slugs dislike such as marigolds.

Spider Mite

Spider mites are yet another insect that is very common in gardens and can be destructive if left untreated. Their favorite hosts are plants that have been stressed by heat and drought.

These insects are tiny and you will likely notice signs of them and not the actual insect. Spider mites use webbing to protect themselves as well as their eggs. Oftentimes this webbing will be noticeable. Their feeding will give leaves a freckled appearance.

Spider mites can easily be prevented by keeping your plants well-watered. Mulching around your plants will help to keep your plants from drying out. Mulching will also help to keep weeds in control. Weeds can suck so much water from plants that they can lead to plant stress. 

If you notice webbing on your plants try hosing the plants off with water. The spray from the hose will disturb the mites and typically remove them entirely from your plant. If you are looking for more control, insecticidal soaps may do the trick.