Mealybugs on Croton Plants
Crotons' flamboyantly patterned yellow, orange, green, pink, red and bronze leaves give flowers a run for their money in U.S. Department of Agriculture plant hardiness zones 9 through 11. In cooler climates, crotons (Codiaeum variegatum var. pictum) bring tropical flash indoors. But crotons lose much of their appeal when messy mealybugs arrive to feed and raise their families.
Mealybugs look more like bits of cotton fluff than bugs, and they like it that way. The insects are named for their secretions of the white or grayish, mealy wax that covers their bodies, sealing out water and -- unfortunately -- water-based insecticides.
To the naked eye, the four species most likely to infest crotons -- obscure, citrus, longtailed and Madeira -- are difficult to distinguish. Obscure and Madeira mealybugs infest both outdoor and indoor crotons. Citrus and longtailed mealybugs only infest the indoor plants.
Croton mealybugs share a particularly annoying habit. After draining sap from the plant's tender new growth and metabolizing its nitrogen, they excrete the carbohydrate-loaded residue as sticky, transparent honeydew.
Besides clinging to the plants and surrounding surfaces, honeydew attracts sooty mold spores that germinate into greasy, black fungal layers.
Cultural Control Methods
Manage an early infestation with household items.
- Crotons arrive to feed and raise their families.
- To the naked eye, the four species most likely to infest crotons -- obscure -- are difficult to distinguish.
Pour a small amount of rubbing alcohol into the jar or cup.
Dip one end of a cotton swab into the alcohol.
Touch the wet end of the swab to a mealybug's back. Repeat for each insect.
Wait 48 hours while the alcohol dissolves the mealybugs' protective wax and kills them.
Connect the spray attachment to a faucet or hose and rinse the dead insects from the plant. Rinsing also dislodges recently hatched mealybugs and egg sacs. If you don't have a spray attachment on your sink, you can also use a showerhead to spray the crotons.
- Pour a small amount of rubbing alcohol into the jar or cup.
- Connect the spray attachment to a faucet or hose and rinse the dead insects from the plant.
Check the leaves' undersides and crotches carefully for concealed mealybugs.
If the alcohol treatment sounds tedious, give lightly infested indoor plants a thorough rinsing in the shower after covering its container in a plastic bag so the potting soil stays put. Rinse outdoor crotons with the hose sprayer set on jet.
Chemical insecticides don't penetrate mealybugs' waxy shields. A better choice for eradicating a severe infestation is organic, ready-to-use insecticidal soap. The soap suffocates the adults and larvae it hits, so complete coverage is essential.
Move indoor crotons to a dimly lit area, or wait until the outdoor ones are out of direct sun.
Cover nearby indoor surfaces to protect them from dripping or drifting spray.
Put on the protective clothing goggles and waterproof gloves.
Spray until the soap runs from all the plants' surfaces. Pay extra attention to the backs of the leaves.
- Chemical insecticides don't penetrate mealybugs' waxy shields.
Repeat the application once or twice over the next three days, or as often as the soap's label recommends, to kill mealybugs that escaped or hatched after the initial treatment.
Always follow an insecticide label's instructions on application rate and frequency as well as its safety precautions.
- UC Statewide IPM Online: Mealybugs
- University of Vermont Entomology Research Laboratory: Common Greenhouse Pests – Mealybugs
- University of Florida IFAS Extension: First Detector -- Mealybugs & Mealybug Look-Alikes of the Southeastern United States
- UC Statewide IPM Online: Mealybug Species
- UC Statewide IPM Online: Pesticide Information -- Active ingredient, Soap