Pink hibiscus mealybugs are oval shaped insects that are pale pink to reddish-brown in color and the insects’ body is covered with white, cotton-like wax. Mealybugs release toxins into plants which lead to curled leaves, stunted growth, and a “bunchy top” appearance (image: idtools.org).
By John Green, Certified Texas Expert Gardener, Orange, TX
Mealybugs are insects from the family Pseudococcidae which contain more than 2000 species. Mealybugs are soft-bodied, unarmored, scale insects commonly found in moist, warm habitats. “Hibiscus mealybug” can refer to a few different mealybug species.The pink hibiscus mealybug is a serious economic threat to agriculture, forestry, and the nursery industry since the pest attacks many plants, trees, and shrubs. Host plants include hibiscus, citrus, sugar cane, annonas, plums, guava, mango, okra, sorrel, teak, mora, pigeon pea, peanut, grape, maize, asparagus, chrysanthemum, beans, cotton, soybean, and cocoa, to name a few. Host plants extend to 76 families and over 200 genera.
As the pink mealybug feeds (using a piercing/ sucking process) it injects the plant with a toxic saliva which culminates in malformed leaves, stunting, and on occasion, plant death. Leaves demonstrate characteristic curling, resembling damage caused by viruses. Plants heavily infested have truncated internodes leading to a “bunchy top” appearance. A heavy, black, sooty mold often develops on an infested plant’s leaves and stems, the result of the mealybug’s honey-dew secretions. If fruits are infested, they can be completely covered with a waxy, white coating of the mealybug. Infestation may lead to fruit drop, or fruit may have a dried or shriveled appearance. If flower blossoms are attacked, fruit set will be minimal.
The two most prevalent hibiscus mealybug types are:
Pink Hibiscus Mealybug (Maconellicoccus hirsutus)- which is pinkish to reddish-brown in color and covered in white, cottony wax. It feeds on plant sap and releases toxins, leading to curled leaves, stunted growth, and a “bunchy top” appearance in hibiscus and other plants.
Hibiscus Mealybug (Nipaecoccus viridis)- which is like the pink hibiscus mealybug but is larger and more distinctly pinkish. It also feeds on plant sap, excreting honeydew (waste) that leads to sooty mold growth which weakens the plant.
General Mealybug Management Approaches
- Water- using a stream of water (the best approach for light infestations) but note that fragile plants will not tolerate rigorous treatment.
- Isopropyl Alcohol- using a soft cloth or cotton ball saturated with isopropyl alcohol that is no more than 70% alcohol since higher concentration will damage plant cellular integrity. Test on one leaf to ensure it will not cause damage before applying it to the entire plant. Remove mealybugs with the cotton ball or soft cloth as the entire plant is treated. Repeat treatment weekly.
- Insecticidal Soap- purchase a commercial insecticidal soap or mix a batch of insecticidal soap by mixing one teaspoon of dish soap with 1 gallon of water. Spray the soap solution on all the plant parts, including the underside of the leaves. Repeat biweekly, weekly, and after rainfall.
- Neem Oil- is an organic insecticide. Create a mixture by adding Neem oil, a mild dish detergent and water (2 tablespoons of neem oil, 2 teaspoons of dish detergent, and 1 gallon of warm water) and follow Neem oil application directions on the products label. The natural substance in neem oil affects mealybug feeding abilities, growth, and development, and acts as a repellent. Repeat weekly.
- Predatory Insects- combatting mealybugs with predatory insects will require the longest amount of time but it is the only approach with beneficial side effects for the garden. Gardeners with severe mealybug infestations need to follow another approach for faster results. Lacebugs, parasitoid wasps and Crypts (known as the mealybug destroyer) are each a natural killer. Make the garden a welcome environment for predatory insects by offering food sources and shelter using host plants that attract them.
- Chemical Pesticides- should always be a gardeners’ last resort and used with extreme caution. Broad-spectrum insecticides indiscriminately kill all insects, including beneficial insects and always contain substances that can be harmful to humans and if used improperly, the environmental. If gardeners must use a chemical pesticide, select a product formulated for use against mealybugs. Read and follow the label directions for application/ reapplication directions.
- Reducing feeding and watering can often prevent mealybugs as it reduces nitrogen levels and hardens a plant’s growth.
It can take weeks or months to control and eradicate mealybugs, depending on the severity of the infestation. Tropical plants and houseplants are especially prone to infestations. There are numerous natural strategies which can help gardeners prevent mealybug infestations on plants. Infestations which cannot be controlled gardeners should consider destroying the plant before the mealybug infestation spreads.
So long for now fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, one ‘pest-free’ plant at a time! For answers to your gardening questions, send me an email: jongreene57@gmail.com.
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