Crepe myrtles, with their vibrant summer blooms and attractive, peeling bark, are a staple in many landscapes. However, like all plants, they can fall prey to pests, one of which is the scale insect.
Scale on crepe myrtles can be a serious issue, affecting the health and appearance of these beautiful trees.
What causes scale on crepe myrtles? Scale on crepe myrtles is primarily caused by scale insects known as crepe myrtle Bark Scale (CMBS). These pests are often introduced through infested plantings or by crawling or flying from an infested tree to a new host. However, they can also spread by wind or by traveling on animals and insects.
If you’re keen on maintaining the health and beauty of your crepe myrtles, understanding and managing bark scale is crucial.
In the following sections, we’ll explain what crepe myrtle bark scale is, its life cycle, how to identify an infestation, and the damage it can cause.
We’ll also provide detailed strategies for preventing and managing this pest.
- Crepe myrtle bark scale is a pest that feeds on the sap of crepe myrtles, causing a range of symptoms and potentially weakening the tree over time. They are white or gray, oval-shaped, and about 2 millimeters long.
- Regular monitoring, proper planting and care, and purchasing healthy plants can help prevent a CMBS infestation.
- If an infestation occurs, it can be managed through cultural practices, biological control, and chemical control methods.
Need a comprehensive resource on crepe myrtle tree problems? Explore my article, Crepe Myrtle Diseases and Pests, for a detailed guide to the most common issues.
Crepe Myrtle Bark Scale
Crepe myrtle bark scale (CMBS) is a relatively new pest that was first identified in the United States in 2004. It’s a type of felt scale and is scientifically known as Eriococcus lagerstroemiae.
CMBS is a small insect, typically measuring only about 2 millimeters in length. Adults are covered in a white or gray waxy material and are often mistaken for a fungal or bacterial disease due to their appearance.
They are most commonly found on the trunk and branches of the tree rather than the leaves.
CMBS is native to Asia and was likely introduced to the United States through the import of infested plants. Since its introduction, it has spread to several states, primarily in the southern U.S.
Crepe Myrtle Bark Scale Life Cycle
The life cycle of CMBS includes four stages: egg, crawler, nymph, and adult.
The females lay pinkish-colored eggs underneath their protective wax coating. When the eggs hatch, the young scales, known as crawlers, move to find a suitable spot to feed.
Once they settle, they insert their feeding tube into the bark and begin to secrete a waxy coating over their bodies, under which they mature.
The entire life cycle from egg to adult can take several weeks to months, depending on environmental conditions.
Identification & Signs of Infestation
Identifying CMBS early can help you manage an infestation more effectively. Here are some signs to look out for:
- Appearance of the Scale: Adult CMBS are white or gray, oval-shaped, and about 2 millimeters long. They are often found in clusters on the bark of the tree.
- Sooty Mold: As CMBS feed on the sap of the tree, they excrete a sugary substance known as honeydew. This can lead to the growth of a black fungus called sooty mold on the bark and leaves of the tree.
- Decline in Tree Health: Infested trees may show signs of stress, such as reduced growth, fewer flowers, or premature leaf drop.
- Damage & Secondary Issues
While CMBS itself does not usually kill crepe myrtles, heavy infestations can weaken the tree and make it more susceptible to other pests and diseases.
The presence of sooty mold can also reduce the tree’s photosynthetic ability and overall vigor.
With proper care and management, most crepe myrtles can recover from a CMBS infestation. It’s important to monitor the tree regularly and take action at the first sign of infestation.
If you suspect an infestation, contact your county extension office to report it and get treatment advice.
Prevention Strategies for Scale on Crepe Myrtle
Prevention is always better than cure, and this holds true for managing CMBS. Here are some strategies to prevent an infestation:
Regular Monitoring: Regularly inspect your crepe myrtles for signs of CMBS, especially during the growing season when the insects are most active.
Proper Planting and Care: Healthy trees are less susceptible to pests. Ensure your crepe myrtles are planted in suitable conditions and receive appropriate water, nutrients, and pruning.
Purchase Healthy Plants: When adding new crepe myrtles to your landscape, ensure they are free of CMBS. Inspect the trunk and branches carefully before purchase.
How To Get Rid of Bark Scale on Crepe Myrtle
If your crepe myrtle is infested with CMBS, there are several strategies you can employ to manage the pest:
Cultural practices involve non-chemical methods that can help reduce the scale population.
Regularly removing and disposing of infested branches can help reduce the scale population. Be sure to dispose of these branches properly to prevent the scales from spreading to other trees.
Washing the tree with a strong jet of water can also dislodge the scales. This is most effective when the scales are in the crawler stage as adults are firmly attached to the tree.
Biological Control Options
Biological control involves using natural enemies of the scale to control their population. Certain insects, such as ladybugs, lacewing larvae, and parasitic wasps, feed on scale insects and can help control their population.
You can encourage these beneficial insects by planting a variety of flowering plants in your landscape and avoiding the use of broad-spectrum insecticides that can harm these beneficial insects.
Chemical Control Methods
In severe infestations, chemical control may be necessary. Horticultural oils and insecticidal soaps in combination with bifenthrin spray can be effective against CMBS.
These work by smothering the scales and are most effective when applied while the scales are in the crawler stage.
Systemic insecticides, such as those containing imidacloprid or dinotefuran, can also be used. These are taken up by the tree and kill the scales when they feed on the tree’s sap.
However, they should be used as a last resort due to their potential impact on non-target organisms and pollinators.
What Is the Best Insecticide for Crepe Myrtle Bark Scale?
The best insecticide for CMBS is one that is effective against scale insects but has minimal impact on beneficial insects.
Horticultural oils and insecticidal soaps mixed with a bifenthrin spray can be effective for crawlers. According to Clemson Cooperative Extension, a soil drench with dinotefuran applied in the spring is ideal.
Do Scale Insects Live in the Soil?
Most scale insects, including CMBS, live on the above-ground parts of plants. However, some species can infest the roots and may live in the soil.
Crepe myrtle bark scale can be a serious pest, but with knowledge and proactive management, you can protect your crepe myrtles and maintain their health and beauty.
Remember that regular monitoring, proper tree care, and early intervention are key to managing this pest.
Crepe Myrtle must deal with various pests and diseases. Here are a few others to learn about: