Hydrangeas are a popular choice in lawns and gardens, thanks to their showy blooms. Some gardeners are concerned, however, that their large hydrangea bushes may be bringing mosquitoes to the yard.
There is no evidence that hydrangeas attract mosquitoes. However, mosquitoes are attracted to standing water and dense vegetation. Since hydrangeas require plenty of moisture, it is possible to create a welcoming environment for mosquitoes, though the hydrangeas themselves are not an attractant.
Let’s take a closer look at what mosquitoes are attracted to, which insects are attracted to hydrangeas, and how to alleviate the number of mosquitoes in your yard.
Best Growing Practices for Hydrangeas
Hydrangeas grow quite quickly in well-drained soils that contain compost or other organic material. They can tolerate a variety of pH levels in the soil. In fact, in acidic soils, their blooms will be blue; in alkaline soils, their blooms will be pink!
Hydrangeas thrive in the morning sun but need shade in the afternoon. North, east, or protected areas of your yard would be ideal planting locations for hydrangeas (source).
Hydrangeas, especially the bigleaf varieties, need a good deal of water, about one inch per week. If you live in an area with little rainfall, plan to irrigate your hydrangeas. Mulching can help maintain soil moisture and temperature levels.
Why These Planting Sites Could Be Problematic
If there’s one thing mosquitoes love, it’s standing water. If you notice that mosquitoes seem to be attracted to a particular area of your yard, standing water is probably the culprit.
Standing water is quite literally a breeding ground for mosquitoes, since that is where they lay their eggs. Even a structure as small as a birdbath can become the birthplace of hundreds of mosquitoes in a matter of days.
Some types of mosquitoes, including Aedes, which is common in many parts of the United States, look specifically for standing water at the base of plants and lay eggs there (source).
Because hydrangeas need quite a bit of water, and because they don’t grow well in hot, dry afternoon sun, their planting locations could be attractive to Aedes mosquitoes looking for a place to lay eggs.
However, this does not mean that mosquitoes are attracted to hydrangeas specifically. Mosquitoes are not known to be picky; any puddle or container of water will do.
Furthermore, this particular problem is easy to mitigate.
- Avoid overwatering your hydrangeas and other plants.
- Water slowly to allow the soil to drain properly.
- Apply mulch at the base of your plants to block mosquitoes’ access.
Insects That Are Attracted to Hydrangeas
Mosquitoes may not be especially attracted to hydrangeas, but other insects are. Some of these insects are benign pollinators like bees, butterflies, and moths (source). Others are pests that you may need to look out for.
Insects that can harm your hydrangeas include the following:
- Black vine weevil
- Four-lined plant bugs
- Rose chafer
- Two-spotted spider mites
In small numbers, aphids are unlikely to cause extensive damage to your hydrangeas. In large numbers, however, they can cause problems.
Aphids excrete a sticky waste called “honeydew.” The honeydew itself won’t damage the hydrangea’s leaves, but it does provide a healthy habitat for black sooty mold. This mold blocks sunlight, inhibiting photosynthesis.
Furthermore, honeydew attracts ants to the point that ants will actually protect aphids from predators.
If you suspect an aphid infestation, spray them off your plant with a hose or use an insecticidal soap (link to Amazon).
Black Vine Weevils
The life cycle of black vine weevils begins in the soil. Larvae eat roots, and if the population is large enough, will girdle large roots and cause the hydrangea to die.
Adult black vine weevils emerge from the soil in the late spring and early summer to eat leaves for a few weeks before returning to the soil to lay eggs.
Black vine weevils are hard to treat, since they can do so much damage before you even know they are there. Some insecticides may be effective, if they are applied after the adults emerge and before they return to the soil (source).
Four-Lined Plant Bugs
Four-lined plant bugs eat away at stems because they lay eggs within the hydrangea’s stem tissue. Once they hatch, they feed on sap from the leaves.
Small populations are not likely to cause extensive damage. Larger populations can be controlled with insecticidal soap (source).
Rose chafers are beetles that can eat away leaves to the point that leaves become skeletonized. They also like to eat hydrangea blooms, especially white ones.
Rose chafers overwinter in sandy soil and larvae eat roots before coming to the surface.
Unfortunately, there is not much you can do to control rose chafer populations. Insecticides haven’t proven effective.
Two-Spotted Spider Mites
If you notice stippling or freckling on your hydrangea leaves, your hydrangea bush may have two-spotted spider mites. Each “freckle” is actually a tiny injury left after mites have fed on the leaves.
The good news is that two-spotted spider mites are prey for other insects. If your hydrangea has been injured by these mites, keep it well-watered during periods of drought to increase the health of the leaves.
Do Any Plants Attract Mosquitoes?
Male mosquitoes rely on nectar from flowers as their only food source. Female mosquitoes also enjoy nectar, but as we know from painful experiences, female mosquitoes also feed on mammals.
The blunt-leaf orchid is the one flower species that scientists are certain mosquitoes find attractive. In fact, mosquitoes are so attracted to the scent of this orchid variety that even when the petals are covered by canvas, mosquitoes will try to feed on the flowers (source).
Mosquitoes don’t seem to have strong preferences for other species of flowers, suggesting that they will take their nectar from what is available, especially if there is standing water nearby.
Unfortunately, there is no surefire way to make your lawn and garden completely free of mosquitoes. However, there are several actions you can take to limit their populations, especially if you can disrupt their life cycles.
Eliminate Sources of Standing Water
As mentioned above, female mosquitoes lay their eggs in or near standing water. The amount of water is inconsequential–even a small puddle will do.
Mosquitoes mature extremely quickly. In warm enough temperatures, an egg can grow into an adult in under one week!
This is why it’s important to look for potential problem areas in your yard before the spring weather becomes warm.
Is there a place where water tends to pool after it rains? Do you have gutters that tend to clog? Do any of your trees have holes large enough to contain water?
Even without an obvious source of standing water, like a pond, there are dozens of ways water may be collecting in your yard. Fortunately, many of these problems can be mitigated.
- Improve the drainage of your soil through fertilization and aeration.
- Remove debris from your gutters to prevent clogging.
- Fill holes in trees.
- Empty containers such as pet dishes and trash cans after it rains.
- Change the water in birdbaths, wading pools, and other small water features at least once a week.
- Keep ponds aerated–mosquitoes are less attracted to moving water (source).
Once mosquitoes hatch, they live in the water throughout their larval and pupal stages. The above actions will not only create an inhospitable breeding environment, but they will make it difficult if not impossible for larvae and pupae to mature.
However, since mosquitoes can mature rapidly, it’s important to consider other methods of control as well.
If you have a pond or other water feature, you can purchase chemical larvicide to kill any mosquito larvae living in the water. The active ingredient in larvicide is methoprene or Bacillus thuringiensis israelensis (Bti).
Both methoprene and Bti are available as granules that you can sprinkle into the water to be digested by mosquito larvae. Even a small amount, less than one teaspoon, can be very effective.
The best news is that neither methoprene nor Bti is toxic to dogs, cats, fish, or humans when used properly (source).
Repelling Adult Mosquitoes
Eliminating standing water and applying larvicide won’t stop adult mosquitoes from flying into your yard. However, there are some simple things you can do to keep them at bay.
- Keep trees and shrubs from becoming overgrown and don’t allow your vegetation to become too dense. Mosquitoes look for protected spots to spend their days.
- Wear mosquito repellent if you plan to spend time outdoors.
- Fans installed on patios and decks can disrupt mosquitoes’ flight paths and keep them from coming too close to you.
- Apply a pyrethroid insecticide to the bases of trees, shrubs, decks, and foundations if the mosquito population becomes intolerable (source).
Are There Any Plants That Repel Mosquitoes?
You have likely heard that plants such as citronella, lemongrass, catnip, and rosemary will repel mosquitoes. There is even a variety of geranium that’s marketed as the “Mosquito Plant” because of its supposedly repellent properties.
The truth is that none of these plants will repel mosquitoes if they’re simply growing in a container or landscape. They do contain oils that repel mosquitoes, but those oils are not released unless the plants’ leaves are destroyed by being burned or crushed.
Many non-DEET bug sprays include essential oils from these plants. These repellents will be much more effective than the plants themselves (source).
If you want to include hydrangeas in your landscape, you can do so with no fear that they will attract swarms of mosquitoes to your yard. As long as your landscape plants aren’t dense and overgrown, they are unlikely to be the reason mosquitoes gather there.
If you want to decrease the mosquito population in your yard, start by looking for standing water, applying insecticide if necessary, and using fans to disrupt their flight paths.