Spider mites are common houseplant pests, and Calathea plants, known for their striking foliage, are particularly susceptible. These tiny arachnids often target Calatheas in indoor environments.
Identifying Spider Mites on Calathea
Identifying spider mites early is crucial for protecting your Calathea from extensive damage. A primary indicator is fine, delicate webbing, particularly on the undersides of leaves and where stems meet the foliage. Mites use these webs for protection and travel. You might also observe tiny, moving specks, which are the mites themselves, usually less than 0.5 mm long, making them difficult to see without close inspection.
The feeding activity of spider mites causes visible damage to the plant’s leaves. Look for small, discolored spots, often described as stippling or tiny yellow/white dots, scattered across the leaf surface. Mites pierce plant cells and extract their contents. As an infestation progresses, leaves may begin to yellow, wilt, curl inward, or become distorted. A simple test involves tapping a leaf over a piece of white paper; if mites are present, tiny specks will fall onto the paper and begin to move.
Why Calathea Are Susceptible to Spider Mites
Calathea plants originate from the warm, humid understory of South American rainforests, making them accustomed to consistent moisture. Indoors, household environments often have much lower humidity, especially during cooler months when heating systems are active. Spider mites thrive in warm, dry conditions. This mismatch creates an ideal breeding ground for these pests.
When the air is too dry, Calathea leaves become stressed and more vulnerable to pest attacks. Their delicate foliage attracts spider mites, which multiply rapidly in dry air. A single female mite can lay hundreds of eggs, with new mites hatching within days, allowing an infestation to quickly escalate.
Treating Spider Mites on Calathea
Treating a spider mite infestation requires prompt and consistent action. Begin by physically removing as many mites as possible; you can wipe the leaves, especially the undersides, with a damp cloth. A thorough rinse under a shower or with a strong stream of water can also dislodge many mites and their webbing. Ensure to support delicate leaves during this process to prevent damage.
For further treatment, horticultural oils or insecticidal soaps are effective options. Insecticidal soaps work by suffocating the mites, and they should be applied thoroughly to all plant surfaces, including the undersides of leaves. Similarly, horticultural oils coat and smother pests. When using these products, it is important to follow label instructions for dilution and application frequency, typically every few days for several weeks, as they do not always kill eggs. Always test the solution on a small, inconspicuous area of the plant first to ensure there is no adverse reaction before treating the entire plant.
Neem oil, a natural insecticide, disrupts the life cycle of spider mites. Mix it with water and a small amount of dish soap to help it emulsify and spread evenly. Apply this mixture as a spray to both the top and bottom surfaces of the leaves, ensuring full coverage. Neem oil can also be used as a systemic treatment by drenching the soil, allowing the plant to absorb it through its roots, providing internal protection against feeding mites. After applying neem oil, keep the Calathea out of direct sunlight for at least a few days, as it can increase the plant’s susceptibility to sunburn.
During treatment, increasing the humidity around your Calathea can help deter spider mites, as they prefer dry conditions. Continue treatment applications for at least three weeks to target successive generations of mites.
Preventing Future Spider Mite Infestations
Preventing spider mite infestations involves maintaining environmental conditions unfavorable to them. Calatheas thrive in high humidity, ideally between 50% to 60%, and consistently above 60% can significantly reduce leaf damage. Regular misting can contribute to higher humidity, but more effective methods include placing the plant on a pebble tray filled with water or using a room humidifier. Grouping plants together can also create a localized microclimate with increased humidity.
Routine inspection is a simple yet effective preventative measure. Regularly check both the top and, especially, the undersides of leaves for any early signs of pests, particularly on new plants. Promptly cleaning leaves with a damp cloth can remove dust and any stray mites. Proper watering, adequate indirect light, and good air circulation keep your Calathea healthy and more resilient to pest pressures.