Discover 10 Invasive Species in Arkansas

Arkansas is a southern state also known as “the Natural State”. This is because this beautiful state is bordered by beautiful mountains and has amazing deep valleys, mountain streams, wetlands, and more. This subtropical state allows much wildlife and plants to thrive. Unfortunately, this also means that Arkansas is a popular destination for invasive species. Invasive species in Arkansas have the potential to threaten native species and have adverse effects on the ecosystem. By recognizing the invasive species in the state, you will be able to play a very important part in maintaining Arkansas’s native species that call the state home.

Here are 10 invasive species that you can find in Arkansas.

Cogongrass (Imperata cylindrica)

Cogongrass, also known as kunai grass, is a species of perennial grass native to Africa and Asia. This species can grow between 2 and 10 feet tall. The leaves narrow at the top to a sharp point. The upper side of the plant near the base is hairy, while the underside of the plant is usually hairless. The cogongrass can penetrate up to 4 feet deep! This plant is unique in that it is highly flammable, even when it is still green. Interestingly, the plant depends on these fires to spread and maintain ecological dominance.

The cogongrass is considered invasive because it can invade pastures, tree plantations, wild lands, and riparian areas. The plants can form dense monoculture and out-compete native vegetation. The cogongrass can grow in the sun or shade and is considered a serious agricultural and environmental pest.

The cogongrass has been found in Arkansas and has been treated with a combination of herbicides to prevent spread. There are also surveying areas so that the spread of cogongrass can be stopped before a full-on invasion begins. This plant is prohibited in the state, so the cogongrass cannot be purchased, sold, or traded. If you do find this plant, make sure to report it so that the plant can be removed as soon as possible.

Tropical Soda Apple (Solanum viarum)

The tropical soda apple is a perennial shrub native to South America. This plant has prickly stems and leaves. The tropical soda apple is large and can grow up to 6 feet tall and wide. The fruit produced resembles small watermelons around ¾ to 1.5 inches in diameter. In each fruit, there are 180 to 420 seeds. Mature fruits are generally yellow in color. The tropical soda apple is capable of producing over 200 fruit per year.

The tropical soda apple is considered invasive because it dominates the understory layer. The dense growth stops native plant species from growing. This plant is also a host for pathogens that can cause disease in vegetables such as eggplant, potatoes, and tomatoes. The seed is easily dispersed, mainly through cattle and wildlife. Although not poisonous to cattle and wildlife, this fruit is poisonous to humans.

Measures such as hand pulling, cutting, and mowing can be used to control the spread of tropical soda apples. To rid mature plants, cutting, piling, and burning will help to kill the seed. Herbicides can also be used to control tropical soda apple invasions.

Chinese Privet (Ligustrum sinense Lour.)

The Chinese privet is an evergreen plant that is native to China. This plant can grow up to 16 feet long with densely hairy shoots. The flowers produced are small and white in color, while the fruit produced is purple or black and considered poisonous. This plant is largely used for ornamental and hedging purposes. This plant was introduced to North America for its hedging and landscaping properties.

The Chinese privet is considered invasive because of many reasons. One of the main reasons is that this plant crowds out native plants and out-competes them for growing space. The plant also does not provide ecological benefits and aids in the degradation of riverbanks and streams. Lastly, the Chinese privet is extremely hardy and can grow and spread quickly, which makes the plant difficult to control and eradicate.

Several control methods are in place to control the Chinese privet and prevent invasion. The most effective method is prevention, which is done by planting native trees instead of this invasive species. Another method is to cut down the Chinese privet and use herbicides to destroy the plant. Other methods, such as pulling out fresh saplings and digging out the plant completely, can also be effective.

Hydrilla (Hydrilla verticillium)

Hydrilla is an aquatic plant native to Asia, Africa, and Australia. This plant has long stems that can grow up to 25 feet long; they also form dense mats at the surface. The leaves of the hydrilla are small, oblong, and toothed. The hydrilla can also produce flowers – inverted bell-shaped green flowers are male, while the small, white flowers are female. 

The hydrilla is considered an invasive species due to its ability to out-compete native species. The plant can also choke off the water body, which negatively affects boating, fishing, swimming, and more. However, with that said, this plant does provide good quality habitat and has some water quality benefits.

An effective control measure for the hydrilla is biological. With the use of a tiny Asian fly, there have been positive effects on the control of the hydrilla. The fly’s larvae only feed on hydrilla, so this is a great control method that does not affect any other plant species.

Boll Weevil (Anthonomus grandis)

The boll weevil is a beetle native to Mexico and Central America. These beetles are generally less than 0.25 inches in length, and they have long snouts and two spurs. The boll weevil is reddish-brown, gray, or black in color. This beetle generally eats cotton plants and other vegetation that is closely related to cotton plants. 

The boll weevil is considered an invasive species because it can cause extensive agricultural problems. Because both the larvae and adult boll weevil feeds on cotton plants, the damage caused to the cotton industry is substantial. In fact, the boll weevil is the most destructive cotton pest in North America.

Although successfully eradicated in Arkansas, the boll weevil is still considered an invasive species because of the damage it can cause. The control measure used to eradicate the boll weevil was the use of insecticides.

Old World Bollworm (Helicoverpa armigera)

The old world bollworm is a moth native to African, Asian, and European continents, and today, this moth is present in over 80 countries and regions, including Arkansas. Adult bollworm moths have a wingspan of around 1.5 inches and are a pale brown or greyish color. The larvae are between 0.5 to 0.75 inches long and are brown in color with darker streaks and spots along their bodies.

The preferred diet of these insects is cotton, corn, tomatoes, and a variety of other plant life. The larvae will feed on the leaves and buds of developing fruits of these plants. Old world bollworms are considered invasive species in Arkansas because they have a rapid reproduction rate and can cause severe damage to crops. The larvae are especially problematic as they tend to feed on the reproductive parts of the plants, which can negatively affect their yield and quality of fruits.

There are a few control methods in place to prevent the spread of this invasive species, including limiting the transport of fresh fruits, vegetables, plants, or soil into the state. Because these moths or larvae can be hiding within shipments, they can easily spread from one place to the next. Trapping and herbicides are also common to kill any established populations and reduce the damage they cause.

Sirex Wood Wasp (Sirex noctilio)

Sirex wood wasps are a species of wasp that has caused severe damage to pine trees around the world. Originating from Europe, Asia, and Africa, they were accidentally introduced to many other countries through the transportation of infested wood. These wasps are just under 1.5 inches in length with slender bodies. The males have shiny black bodies with orange legs, while the females are metallic blue and have yellowish wings.

The Sirex wood wasps have a very unique feeding technique. Female wasps will carry spores of a fungus called Amylostereum areolatum, which she will introduce to the wood of pine trees. This fungus will grow within the tree and will soften and decompose the wood, which the wasps will then eat. Unfortunately, this is not so good for the host tree, and it will begin to die. For this reason, the Sirex wood wasp is considered invasive to Arkansas due to its ability to affect huge populations of pine trees.

The state is proposing new rules for the import of materials that may contain the sirex wood wasps or their larvae. This would help prevent any further introduction of the species into Arkansas. Early detection of the wasps also helps to eliminate them before they can get properly established.

Emerald Ash Borer (Agrilus planipennis)

The emerald ash borer is a type of beetle native to northeastern Asia. This beetle gets its name from its striking emerald color. Emerald ash borers are small and are around 0.33 inches long and 0.06 inches wide.

The emerald ash borer is invasive due to its feeding habits. As the name suggests, adult emerald ash borers’ main diet is ash tree leaves. Furthermore, the larvae of the emerald ash borers feed on the vascular tissue of an ash tree. The larvae make distinct S-shaped lines in the bark of the trees. Unfortunately, because North America does not have resistant trees, predators, or parasitoid wasps to control the emerald ash borer populations, these insects keep reproducing, and populations keep rising. The emerald ash borer has killed tens of millions of ash trees and continues to threaten all the other remaining ash trees in the country. Of course, this also negatively impacts the ecosystem, as these invasive insects harm many native plants and species.

Unfortunately, the emerald ash borer has already been found in Arkansas, and there has been a statewide quarantine for ash items since 2018. This is because the quickest way for the beetle to travel is by human transportation of the beetle. Trapping for the emerald ash borer was initiated in 2010. Even biological control agents or parasitoids were released to help control emerald ash borer populations. 

Channeled Apple Snail (Pomacea canaliculata)

The channeled apple snail is a freshwater snail native to South America. It is a large snail with a shell capable of reaching up to an incredible 2.4 inches in diameter. And the brown or black body of the channeled apple snail can be over 3 inches in length. These snails have gills that allow them to breathe underwater. They also have a distinctive snorkel that emerges when the snail is submerged in water.

The channeled apple snail is considered invasive due to its voracious appetite and ability to reproduce quickly. The snail’s diet includes aquatic plants like rice, water lettuce, algae, and more. This mollusk’s ability to reproduce quickly means that the populations of the channeled apple snail can become large, making it more difficult for native species to compete. The channeled apple snail also causes damage to crops and irrigation systems – they especially pose a threat to rice and natural wetlands.

These snails were once sold in aquariums. To control the channeled apple snail population, make sure that you do not release these snails if you have them already! There are no known chemicals that can selectively eradicate the channeled apple snail, making it incredibly hard to control populations. And if you see channeled apple snail eggs, which look like red or pink masses above the water’s surface, notify the Arkansas State Plant Board.

Northern Snakehead (Channa argus)

The northern snakehead is a freshwater fish that is native to East Asia. This fish is an important food source, which is why the fish is now found throughout the world, including in Arkansas. The northern snakehead has a long dorsal fin, an extended anal fin, a snake-like head (hence its name), and a large mouth. These fish can grow quite large and have been reported to reach up to 3’3” in length. The northern snakehead is golden tan to pale brown in color and has dark blotches on the side. One interesting fact about these fish is that they are obligate air breathers.

The northern snakehead is an invasive species in Arkansas because it preys on and competes with native species. The diet of the northern snakehead mainly consists of other fish species, but they also eat crustaceans, reptiles, mammals, and small birds. This invasive species can reduce or eliminate native fish populations and even alter the aquatic ecosystem.

If you come across a northern snakehead in Arkansas, you must kill it immediately and report the encounter. You must report your encounter as having a live or dead northern snakehead in your possession is illegal. And reporting the encounter helps mitigate the negative impact this species can have on native species.

Summary of Invasive Species in Arkansas