Identifying and dealing with boxwood caterpillar

Buxus plants, commonly known as boxwoods, are popular choices for hedges, topiaries, and ornamental shrubs in gardens and landscapes. However, these beloved plants are susceptible to damage from caterpillar infestations, which can have a significant impact on their health and appearance. Understanding the effects of caterpillar damage on Buxus plants is essential for effective pest management and preserving the vitality of these cherished shrubs.

Caterpillars, the larval stage of butterflies and moths, can cause substantial damage to Buxus plants through their feeding habits. The most common culprits include the box tree moth (Cydalima perspectalis) and the boxwood caterpillar (Diaphania perspectalis). These voracious feeders consume Buxus leaves, leading to defoliation and weakening of the plants. As a result, the aesthetic appeal of the Buxus is compromised, and the overall health and vigor of the plants are jeopardized.

Signs of caterpillar damage on Buxus plants often manifest as skeletonized or chewed leaves, webbing, and frass (insect excrement) on the foliage. Severe infestations can cause extensive defoliation, leaving the plants vulnerable to stress, disease, and environmental pressures. Additionally, the aesthetic value of the Buxus is significantly diminished, impacting the overall visual appeal of the landscape.

Beyond the visible damage to foliage, caterpillar infestations can weaken Buxus plants, making them more susceptible to other pests and diseases. The loss of leaves reduces the plant’s ability to photosynthesize and store energy, potentially leading to stunted growth and diminished resilience. Furthermore, repeated defoliation due to caterpillar feeding can compromise the long-term health and survival of Buxus plants, particularly in instances of recurrent infestations.

Mitigating Caterpillar Damage: To mitigate the impact of caterpillar infestations on Buxus plants, proactive pest management strategies are crucial. Regular monitoring for early signs of caterpillar activity, such as eggs, larvae, or feeding damage, allows for timely intervention. Non-chemical control measures, such as handpicking caterpillars, applying horticultural oils or insecticidal soaps, and encouraging natural predators, can help manage infestations while minimizing environmental impact.

One common method of control we have used is Xentari which is a biological insecticide that contains the active ingredient Bacillus thuringiensis subspecies aizawai (Bta). This microbial insecticide is commonly used to control various caterpillar pests, including the boxwood caterpillar (Diaphania perspectalis). When applied correctly, Xentari can be an effective and environmentally friendly solution for managing caterpillar infestations on boxwood plants.

Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium that produces proteins toxic to certain insect larvae, including caterpillars. When ingested by susceptible caterpillars, the Bt proteins disrupt their digestive systems, leading to paralysis and eventual death. Xentari, formulated with Bt subspecies aizawai, specifically targets caterpillars and is known for its efficacy against a wide range of moth and butterfly larvae, including the boxwood caterpillar.

When using Xentari to control boxwood caterpillars, it is important to follow the product label instructions carefully. This includes applying the product at the recommended rate and timing, ensuring thorough coverage of the foliage where caterpillars are present. Xentari is most effective when caterpillars are actively feeding, so timing the application to coincide with their presence is crucial for optimal control.

One of the advantages of using Xentari for boxwood caterpillar management is its selective toxicity, which means that it primarily affects caterpillars and has minimal impact on beneficial insects, birds, and mammals. As a biological insecticide, Xentari is considered an environmentally friendly option for controlling caterpillar pests, particularly in situations where minimizing non-target effects is a priority.

Caterpillar infestations pose a significant threat to the health and aesthetics of Buxus plants. By recognizing the symptoms of caterpillar infestations and employing appropriate control measures, gardeners and landscapers can safeguard their Buxus plants from the detrimental effects of caterpillar feeding. Alternatively what has been a popular choice for many years since the introduction of box blight is to look into suitable alternative plantings options. Ilex crenata, Lonicera, Taxus baccata, pittosporums are just a few of many alternative options to our much loved buxus plants.