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Do Pests Eat Boxwoods? A Comprehensive Guide to Protecting Your Evergreens

Yes, pests definitely eat boxwoods. While renowned for their durability and elegant appearance, boxwoods are unfortunately susceptible to a variety of insect infestations that can cause significant damage, even death, if left untreated. Understanding the common culprits and implementing preventative measures is crucial for maintaining healthy and thriving boxwood shrubs.

Identifying the Culprits: Common Boxwood Pests

Boxwoods, particularly Buxus sempervirens, are a favored target for several pests. Identifying the specific pest attacking your shrubs is the first step in effective treatment.

Boxwood Leafminer ( Monarthropalpus flavus)

The boxwood leafminer is arguably the most common and destructive boxwood pest. This tiny fly lays its eggs within the leaves, and the larvae then tunnel and feed between the leaf surfaces, creating unsightly blisters. These blisters eventually turn brown and can significantly detract from the plant’s appearance. Heavy infestations can weaken the plant, making it more vulnerable to other stressors.

Boxwood Mite (Eurytetranychus buxi)

Boxwood mites are another frequent offender. These microscopic pests suck the sap from boxwood leaves, causing a stippled or bronzed appearance. Close inspection with a magnifying glass will often reveal the mites themselves and their webbing. Mite infestations can stunt growth and lead to leaf drop.

Boxwood Psyllid (Psylla buxi)

The boxwood psyllid is unique in that it causes cupping or distortion of new growth. These small, aphid-like insects feed on the sap of developing leaves, causing them to curl inward, resembling tiny spoons. While psyllid damage is often more cosmetic than severely damaging, heavy infestations can impact the plant’s overall health.

Scale Insects (Various species)

Several species of scale insects can infest boxwoods, including oystershell scale, euonymus scale, and cottony camellia scale. These pests are characterized by their hard, protective shells, which make them difficult to control. They attach themselves to stems and leaves, sucking sap and weakening the plant. Scale infestations can result in yellowing leaves, stunted growth, and even branch dieback.

Nematodes (Various species)

While not always visible above ground, nematodes are microscopic roundworms that live in the soil and feed on plant roots. Some nematode species can cause significant damage to boxwood roots, leading to symptoms such as yellowing leaves, stunted growth, and wilting.

Recognizing the Symptoms: Signs of Infestation

Early detection is key to preventing widespread damage from boxwood pests. Regularly inspect your plants for the following signs:

Blistered leaves: A telltale sign of boxwood leafminer.
Stippled or bronzed leaves: Indicates a possible mite infestation.
Cupped or distorted new growth: Suggests boxwood psyllid activity.
Yellowing or browning leaves: Can be caused by a variety of pests, including mites, scale, and nematodes.
Stunted growth: A general symptom of pest infestation, stress, or disease.
Branch dieback: Indicates a severe infestation or underlying health problem.
Visible insects or webbing: Allows for direct identification of the pest.
Presence of hard, scale-like bumps on stems and leaves: Indicates scale infestation.

Prevention and Control: Protecting Your Boxwoods

Implementing a combination of preventative measures and appropriate control strategies is essential for maintaining healthy boxwoods.

Preventative Measures

Choose resistant varieties: Opt for boxwood cultivars known for their resistance to certain pests.
Maintain healthy plants: Ensure proper watering, fertilization, and pruning to promote plant vigor. Healthy plants are better able to withstand pest infestations.
Proper planting location: Choose a site with well-drained soil and adequate sunlight.
Regular inspection: Regularly inspect your boxwoods for signs of pests. Early detection allows for quicker and more effective treatment.
Good sanitation: Remove fallen leaves and debris from around the base of the plants to eliminate potential overwintering sites for pests.
Encourage beneficial insects: Attract beneficial insects, such as ladybugs and lacewings, which prey on boxwood pests.

Control Strategies

Horticultural oil: A safe and effective option for controlling many boxwood pests, including mites, scale, and psyllids. Apply in early spring before new growth emerges.
Insecticidal soap: Another environmentally friendly option for controlling soft-bodied pests such as mites and psyllids.
Systemic insecticides: These insecticides are absorbed by the plant and can provide long-lasting control of pests such as leafminers and scale. Use with caution and follow label instructions carefully.
Pruning: Prune out heavily infested branches to remove pests and improve air circulation.
Nematode control: If nematodes are suspected, soil testing can confirm their presence. Nematicides can be used to control nematode populations, but they should be used with caution and only when necessary.

FAQs: Addressing Common Concerns about Boxwood Pests

FAQ 1: What makes boxwoods so susceptible to pests?

Boxwoods, while generally hardy, can be susceptible to pests due to several factors. Their dense foliage provides shelter and a humid environment favorable for certain insects and mites. Additionally, some cultivars are more prone to infestation than others. Stressed or unhealthy plants are also more vulnerable to pest attacks.

FAQ 2: Are boxwood leafminers active year-round?

No, boxwood leafminer larvae are active primarily within the leaves during the growing season. Adult flies emerge in spring to lay eggs, and the larvae then feed and develop within the leaves throughout the summer and fall. They overwinter as larvae within the leaves and pupate in the spring.

FAQ 3: How can I tell the difference between boxwood mite damage and nutrient deficiency?

While both can cause yellowing or browning leaves, boxwood mite damage typically appears as a fine stippling or bronzing on the leaves. Nutrient deficiency usually results in a more uniform yellowing or chlorosis. Using a magnifying glass to inspect the leaves for mites and their webbing is the best way to confirm a mite infestation.

FAQ 4: Can I control boxwood psyllids naturally?

Yes, several natural control methods can be effective against boxwood psyllids. Pruning out infested shoots can remove many of the pests. Horticultural oil or insecticidal soap can also be used to control psyllids. Encouraging beneficial insects such as ladybugs and lacewings can also help to keep psyllid populations in check.

FAQ 5: When is the best time to treat for boxwood leafminers?

The best time to treat for boxwood leafminers depends on the type of insecticide used. Systemic insecticides are most effective when applied in the fall or early spring, allowing the plant to absorb the insecticide before the larvae become active. Contact insecticides are most effective when applied during the adult fly emergence in the spring.

FAQ 6: How often should I apply horticultural oil to my boxwoods?

The frequency of horticultural oil applications depends on the pest and the severity of the infestation. Generally, one or two applications in early spring, before new growth emerges, are sufficient for controlling many pests. Always follow the label instructions carefully.

FAQ 7: Are some boxwood varieties more resistant to pests than others?

Yes, some boxwood varieties exhibit greater resistance to certain pests. For example, ‘Winter Gem’ and ‘Green Velvet’ are considered relatively resistant to boxwood leafminers. Researching pest resistance when selecting boxwood varieties is a wise preventative measure.

FAQ 8: What is the best way to diagnose a nematode infestation in boxwoods?

The only way to definitively diagnose a nematode infestation is through soil testing. A soil sample should be sent to a reputable laboratory for analysis. The results will indicate the presence and type of nematodes in the soil.

FAQ 9: Can I use the same insecticide to treat all boxwood pests?

No, different insecticides are effective against different pests. It is important to identify the specific pest infesting your boxwoods and choose an insecticide that is specifically labeled for that pest. Always read and follow the label instructions carefully.

FAQ 10: Will a severe boxwood pest infestation always kill the plant?

Not necessarily. While a severe pest infestation can weaken a boxwood and make it more susceptible to other stresses, it does not always lead to death. With proper treatment and care, many boxwoods can recover from even severe infestations.

FAQ 11: Are there any organic options for controlling scale insects on boxwoods?

Yes, organic options exist for controlling scale insects. Horticultural oil is effective at smothering scale insects, especially when they are in their crawler stage. Pruning out heavily infested branches can also help to reduce scale populations.

FAQ 12: How important is proper pruning for preventing boxwood pest problems?

Proper pruning is crucial for preventing boxwood pest problems. Pruning improves air circulation, which can reduce the humidity that favors some pests. It also allows you to remove infested branches and improve the overall health and vigor of the plant. Remember to sanitize pruning tools between cuts to prevent the spread of disease.