In recent developments, a beloved staple of Southern landscapes, the crape myrtle, is facing an alarming threat. An invasive insect, the crape myrtle bark scale (CMBS), has made its way into East Texas, leaving the future of this iconic plant species uncertain. Experts, including Dr. David Creech, a Professor Emeritus at Stephen F. Austin State University and Director of SFA Gardens, are sounding the alarm. The invasion of CMBS is serious and could have devastating effects on crape myrtles and other important plant species across the South.
A New Threat in Town
Crape myrtles, cherished for their vibrant blooms and resilient nature, are now under attack by an invasive species originally from Asia. The crape myrtle bark scale (Acanthacoccus lagerstroemiae) was first identified in the United States in Richardson, Texas, in 2004. Over the years, it has slowly but steadily spread across the Gulf South and recently emerged in East Texas, with signs of infestation also surfacing along the East Coast.
Dr. Creech, along with colleagues Greg Grant and Dawn Stover, has been monitoring the situation for years. However, it was only recently that Stover made the unfortunate discovery of the pest in Nacogdoches, Texas. While scouting a local eatery on North Street, she spotted the telltale signs of CMBS infestation and alerted Dr. Creech. The presence of this invasive insect is now confirmed in the region, raising concerns about its potential impact on the local environment.
The Growing Problem of CMBS
The crape myrtle bark scale is easily identifiable, and the consequences of its presence are unmistakable. During its crawler stage, CMBS produces a distinctive pinkish juice when pressed, which makes it relatively simple to diagnose. In severe infestations, the effects are devastating. Branches begin to die, flowers shrink, and the overall health of the tree deteriorates, leaving behind an unsightly landscape that saddens gardeners and nature lovers alike.
One of the most problematic aspects of CMBS infestations is the production of honeydew, a sticky substance that leads to the growth of sooty mold. This black coating attracts aphids, ants, and wasps, further aggravating the condition of the tree. As the pest population grows, entire trees can become covered in black mold, making them a far cry from the majestic, flowering trees they once were.
Perhaps even more concerning is how CMBS spreads. The pest can travel short distances through the air, but it is also carried over longer distances by birds, small animals, and landscaping crews. This makes controlling its spread a challenge. As Dr. Creech notes, once the pest takes hold in a community, it often takes about ten years before the situation reaches a crisis point. The case of Shreveport, Louisiana, where the streets are now lined with heavily infested trees, serves as a stark warning for other communities.
Widespread Impact Across the South
Since its first appearance in Texas in 2004, CMBS has steadily advanced across the southern United States. By 2012, the insect had been reported in Ardmore, Oklahoma, and Shreveport, Louisiana. The following year, sightings were confirmed in Tyler, Texas; Houma, Louisiana; and Germantown, Tennessee. More recently, in 2014, CMBS was found as far east as Little Rock, Arkansas, and the crape myrtle collection at Norfolk Botanical Garden near Virginia Beach, Virginia. The pest’s range now covers much of Zone 7 to Zone 9, and its relentless march shows no signs of slowing.
The economic implications of CMBS are also significant. Crape myrtles represent a $66 million industry at the nursery level, and the pest’s spread could have dire consequences for growers. But the financial losses are just one side of the story. The real danger lies in the ecological impact of CMBS, which now appears capable of attacking several other plant species that are vital to the southern landscape.
A Broader Ecological Concern
While CMBS primarily targets crape myrtles, recent evidence suggests that the insect can also complete its life cycle on other plants, including the American beautyberry (Callicarpa americana). This native plant, common in the forests of the Gulf South, is integral to the region’s ecosystem, supporting both pollinators and wildlife. Beautyberries provide essential food for birds and other animals, making them a critical component of the local habitat.
Unfortunately, the problem doesn’t end there. CMBS has also been known to infest a variety of other plants, including boxwoods, cleyera, fig, persimmon, and pomegranate. In particular, persimmons and beautyberries play vital roles in maintaining the health and balance of the southern forest ecosystem. The ability of CMBS to infest these plants raises serious concerns about the broader environmental impact of the pest.
Potential Solutions and Challenges
While the situation appears grim, there are ways to combat CMBS infestations. However, controlling the pest is not as simple as applying traditional methods used for other types of scale insects. Dormant oils, commonly effective against many types of scale, have proven less successful in combating CMBS. Instead, a class of insecticides known as neonicotinoids has shown promise in controlling the pest. These chemicals, which are derived from nicotine, are much more toxic to insects than to mammals, birds, and other higher organisms.
That said, neonicotinoids come with their own set of concerns. There is ongoing debate about the potential link between these insecticides and the decline in honey bee populations. While the final verdict on their impact remains unresolved, there are guidelines in place to minimize risks to pollinators. Gardeners and professionals are advised to follow label instructions carefully, apply treatments to the soil rather than directly to plants, and avoid using neonicotinoids when bees are active, such as during the daytime.
Hope for the Future
While CMBS poses a serious threat to crape myrtles and other plant species, there is some hope on the horizon. Researchers are working to determine whether certain varieties of crape myrtles may be more resistant to the pest than others. In the meantime, careful monitoring and treatment are essential to prevent the spread of CMBS and mitigate its impact on both the economy and the environment.
As gardeners and horticulturists across the South brace for the continued advance of this invasive insect, it is clear that the battle against CMBS will require vigilance, research, and coordinated efforts. The future of crape myrtles, as well as the health of the southern ecosystem, depends on it.
