Spider mites are tiny pests you cannot see with the naked eye. Yet, they cause intense damage to hibiscus plants once they multiply. Worse, you’ll never notice the spider mites on your hibiscus since they hide under the leaves and buds. You’ll only realize them after seeing damage on your plant.
Spider mites pierce and damage hibiscus foliage, buds, and flowers as they feed, leaving white dots on the leaves (stippling). Blast the spider mites with a jet of water under high pressure to wash them off the plant. You can also spray neem oil or insecticidal soap on your hibiscus to kill spider mites.
What are spider mites?
Spider mites are tiny arachnids that belong to the Tetranychidae family. They have tiny bodies taht make it difficult to see them with your naked eye. An adult spider mite is the same size as a dot on paper or the size of a grain of sand.
The two-spotted spider mite is the most common mite found on hibiscus and other houseplants.
According to the University of Minnesota, the two-spotted spider mite has a small body of about 1/50 inches. The body is oval-shaped, greenish or brown, with two noticeable dark dots on either side.
The two-spotted spider mite is a warm-season mite that actively feeds and multiplies in summer but goes dormant in winter.
Under optimal conditions (temperatures of 86 and humidity below 50%), a spider mite can complete its life cycle within one to two weeks.
The life cycle starts with a female mite laying eggs, sometimes even without mating. The ability of a female mite to reproduce even without a male mite is why spider mites can multiply and cause damage to your houseplants fast. Each female spider mite can lay up to five eggs daily, which hatch into larvae after a few days.
The larva starts feeding immediately. After the larval stage, the spider mites undergo the protonymph and deutonymph stages before becoming adults.
Signs of spider mite damage
To identify spider mites on the hibiscus, check for changes in your plant since you won’t see the tiny insects with your naked eye.
The two-spotted spider mites hide under the leaves and pierce the cell tissues to suck the cell sap. At the start of the infestation, you’ll see changes from the plant’s lower parts, which progress to the upper parts.
Here are the main signs of spider mites on hibiscus:
Small white-yellow patches on leaves
At the start of spider mites infestation, small patches form on the leaves’ undersides, near the base of the leaf vein. These small patches are injury marks that result from piercing the outer cell tissues to suck the cell sap.
The two-spotted spider mite hides under the leaves and pierces the outer cell tissues to suck the cell sap. As a result, the outer cell tissues suffer injuries visible as small patches or dots.
Stippling and bronzing leaves
As the spider mites pierce and suck the cell sap, they leave white or yellow dots or flecks known as stippling.
The white or yellow dots form from mites feeding on chlorophyll, leaving them with non around the pierced spot.
In other cases, brown or grayish flecks form instead of white or yellow dots. This is known as bronzing.
Fine webs around the branches and leaves
Lastly, spider mites form fine webs around the branches and leaves, visible to the naked eye. If the infestation continues, the hibiscus leaves drop prematurely.
Premature leaf dropping
Massive spider mite infestation causes the hibiscus to drop its leaves prematurely.
A gritty, dirty feeling of the leaves
A hibiscus plant with a massive spider mites infestation feels rough and looks dirty. As the spider mites live under the leaves, they drop feces, some die, and others shade their outer skin. These wastes collect and build up on the leaf’s surface, leaving a gritty, dirty feeling when touched.
Treatment and Control for Spider Mites on Hibiscus
If your hibiscus plant is heavily infested with spider mites to the point of fine webbing and premature leaf dropping, it’ll be difficult to cure it. Discard the plant by wrapping it in a plastic bag to prevent the mites from escaping to nearby plants. Dispose of the sick plant in a waste bin.
Meanwhile, hibiscus plants with few mites can be recovered by eliminating the mites. Here’s how to remove spider mites on hibiscus.
- Cut and remove infested leaves, stems, and branches and dispose of them.
- Blast the spider mites with a jet of water under high pressure to wash them and their eggs from the plant.
- Spray the plant with a dilute insecticidal soap of 1-3% concentration to kill the mites.
- Alternatively, spray the hibiscus with neem oil to smother the mites and their eggs.
After removing spider mites from the hibiscus, incorporate protective measures against re-infestation. Here’s how to control spider mites on hibiscus.
1. Treat your plant with neem oil
Insecticidal soaps and neem oil eliminate spider mites and prevent them from reinfesting your plant. They smother the mites to kill them. Occasionally, spray your hibiscus with dilute insecticidal soap or neem oil to keep mites away.
2. Mist the plant regularly
Spider mites thrive in hot and dry conditions and prefer dusty houseplants. Mist the hibiscus with water from a spray bottle to keep them away. Misting also keeps the plant’s area humid.
3. Provide proper care for hibiscus
Growing hibiscus plant under unfavorable conditions makes them susceptible to pests like spider mites.
L. D. Godfrey, an entomologist at the University of California Statewide Integrated Pest Management Program notes that water-stressed plants are much more vulnerable to spider mite damage. (Source)
- Water the hibiscus plant regularly to avoid dry soils that attract spider mites. Check the potting soil and water if the first half inches are dry.
- Mist your plant and add a humidifier to increase air moisture, discouraging mites from living on your plant.
- Lastly, maintain indoor temperature to 65 to 75°F to favor hibiscus. Temperatures above 85 degrees favor the spider mites.
I find that washing hibiscus and other indoor plants with water during dusty seasons helps prevent spider mite infestations.
I also recommend forcefully spraying outdoor hibiscus with water to eliminate and prevent spider mites from the plants. Ensure you get extensive coverage especially on the underside of the leaves where spider mites like to hide.
4. Introduce spider mite predators
Biologically, you can introduce other insect predators to your hibiscus plants to suppress spider mites or manage their population.
For example, mite species such as Amblyseius andersoni, Galendromus occidentalis, Neoseiulus californicus, Neoseiulus fallacies, and Phytoseiulus persimilis are predators of the two-spotted spider mites.
Visit your biological control agent and ask for predatory mites to keep spider mites away.
5. Chemical control
Lastly, you can kill spider mites and aphids on your hibiscus plants using chemical insecticides. I don’t recommend this method unless you’re dealing with a large-scale infestation in your hibiscus plantation.
Research has found that severe outbreaks of spider mites can be occasioned by using insecticides such as carbaryl (Sevin) in plantations. This chemical kills most spider mite predators, leaving the culprit pest to reproduce quickly. (See source).
Insecticides based on hexythiazox, bifenthrin, abamectin, and acephate as active ingredients are recommended for controlling spider mites in yards and gardens but not on individual plants.
Some brand-name products you can use include Arvid, Orthene, Hexygon, and Talstar. Follow the manufacturer’s directions on the label when using these insecticides to control spider mites on your plants.
Spider mites are small pests that can lead to plant loss. Although you cannot see them without magnification, you know they are present if you notice small patches, stippling and bronzing leaves, and fine webs around the plant. Blast the mites with water or spray insecticidal soap.
Keep optimal conditions and mist regularly to control the spider mites.