Invasive Insects in Texas: Watch for These 10 Destructive Species

Texas agriculture officials issued an urgent alert in December 2024—a never-before-seen invasive pest has spread across more than 20 counties, threatening grazing lands and livestock operations. This pasture mealybug represents just one wave in a continuous invasion affecting the Lone Star State.

From fire ants that have dominated Texas landscapes since the 1950s to newly detected citrus threats endangering the state’s $300 million citrus industry, invasive insects in Texas create cascading economic and environmental damage.

You’ll encounter these destructive species whether you’re managing farmland, maintaining a backyard garden, or simply living in areas where these invaders have established populations.

1. Red Imported Fire Ant

The red imported fire ant (Solenopsis invicta) stands as Texas’s most notorious invasive insect, having arrived from South America through the Port of Mobile, Alabama, in the 1930s and spreading throughout the state by the 1950s. These aggressive ants build large mounds in open areas and deliver painful, venomous stings that can cause severe allergic reactions.

Worker ants range from one-eighth to one-quarter inch long with reddish-brown to reddish-black coloring. Their most distinctive characteristic isn’t appearance but behavior—when mounds are disturbed, hundreds of workers swarm out, climbing on the intruder and stinging in coordinated attacks. A single colony may contain 100,000 to 500,000 workers and multiple queens.

Fire ant mounds appear in lawns, parks, agricultural fields, and along roadsides, reaching up to 18 inches high and 24 inches across in established colonies. They prefer sunny, open areas with disturbed soil but adapt to various environments. The ants inflict immediate burning sensations when stinging, with distinctive white pustules forming within 24 hours. Multiple stings are common since ants attack in groups, and some individuals experience severe allergic reactions requiring immediate medical attention.

Key Insight: The “Texas Two-Step Method” represents the most effective proven approach for managing fire ants organically. This strategy combines broadcast bait application followed by individual mound treatments, reducing populations without harsh chemicals.

Beyond human health concerns, red imported fire ants create substantial ecological and economic damage. They reduce native ant populations through aggressive competition, prey on ground-nesting birds and reptile eggs, and alter soil chemistry through extensive tunneling. In agricultural settings, they damage crops by protecting and farming honeydew-producing insects like aphids, which harm plants while providing food for ant colonies. Fire ants also damage electrical equipment and utility housings, causing power outages and equipment failures.

Texas A&M AgriLife Extension researchers have made progress introducing natural enemies including phorid flies—small flies that decapitate fire ants—and Thelohania solenopsae, a disease organism that weakens colonies. Management for homeowners includes broadcast baiting in spring and fall when ants actively forage, followed by individual mound treatments with approved products. Large-scale agricultural or natural area management may employ broadcast baiting programs combined with biological control releases.

2. Emerald Ash Borer

The emerald ash borer (Agrilus planipennis) was first discovered in Texas in 2016 and has since spread to 31 counties as of 2024, representing one of the most destructive invasive insects affecting North American forests. This metallic-green beetle from Asia kills all species of ash trees, even healthy, vigorous specimens.

Adult beetles measure approximately half an inch long and one-eighth inch wide with dark emerald-green bodies that shimmer distinctively. Their larvae cause the actual damage, boring beneath bark and creating serpentine S-shaped galleries that disrupt the tree’s ability to transport water and nutrients. Infested ash trees show symptoms including dead branches near the top, leafy shoots sprouting from the trunk, bark splits exposing larval galleries, extensive woodpecker activity, and distinctive D-shaped exit holes where adult beetles emerged.

The Texas A&M Forest Service confirms that all ash species are susceptible to emerald ash borer. Infested trees may show few to no symptoms in early stages, making regular inspection critical for early detection. The service recommends diversifying tree and plant species to minimize spread impact, as depending heavily on ash trees increases vulnerability to widespread loss.

Texas residents can be proactive in preventing emerald ash borer spread by burning firewood where it’s bought rather than transporting it long distances. The insects hitchhike in firewood, making human-mediated movement the primary spread mechanism. Homeowners with valuable ash trees should consult certified arborists about systemic insecticide treatments, which work best when applied before significant damage occurs. Once ash trees show extensive canopy thinning, treatment may no longer be effective, and removal becomes necessary to prevent trees from becoming hazards.

3. Asian Citrus Psyllid

The Asian citrus psyllid (Diaphorina citri) poses an existential threat to Texas’s $300 million citrus industry by vectoring huanglongbing (HLB), also called citrus greening disease—the most devastating citrus disease worldwide. While the insect arrived in Texas in the early 2000s, the disease it carries continues spreading, with no cure available for infected trees.

Adult psyllids measure approximately one-eighth inch long with mottled brown bodies and clear wings. They hold their bodies at a distinctive 45-degree angle when feeding, making identification easier. Nymphs appear flat and oval-shaped, producing white, waxy tubules as they feed on new citrus growth. Both adults and nymphs use piercing-sucking mouthparts to extract sap from young leaves and shoots.

Pro Tip: Asian citrus psyllids prefer feeding on flush growth—the young, tender shoots that citrus trees produce. Monitoring trees during flush periods provides the best opportunity for early detection and management.

The insect itself causes minor direct damage through feeding, but its role as a disease vector creates catastrophic consequences. HLB-infected trees produce misshapen, bitter fruit that remains partially green, drastically reducing both yield and quality. Infected trees gradually decline over several years, eventually dying. Once a tree becomes infected, no treatment can cure it, making prevention through psyllid control absolutely critical.

Texas citrus growers implement intensive management programs combining:

• Regular psyllid monitoring using yellow sticky traps and visual inspection during flush periods
• Coordinated area-wide insecticide applications timed to population peaks
• Removal and destruction of infected trees to reduce disease reservoirs
• Biological control using Tamarixia radiata, a tiny parasitic wasp imported from Asia that attacks psyllid nymphs
• Regulatory inspections and quarantines to slow disease spread

Homeowners with backyard citrus trees in affected areas should inspect trees regularly for psyllids, particularly during flush growth periods. Washing psyllids off with strong water sprays provides some control, while horticultural oils or insecticidal soaps offer low-toxicity management options. However, coordination with area-wide programs provides the most effective protection for both commercial and residential citrus.

4. Mexican Fruit Fly

The Mexican fruit fly (Anastrepha ludens) creates ongoing concerns for Texas fruit and vegetable production, particularly in the Rio Grande Valley where the insect regularly enters from Mexico. This invasive pest attacks citrus, mangoes, and numerous other fruits, causing millions of dollars in crop losses and trade restrictions.

Adult flies measure approximately half an inch long with yellow-brown bodies and distinctive banded patterns on their wings. Females possess a sharp ovipositor for piercing fruit skin to lay eggs inside. The larvae—white, legless maggots—develop within the fruit flesh, tunneling and feeding as they grow. Infested fruit shows external dimpling or soft spots where larvae feed internally.

The Mexican fruit fly’s wide host range includes:

• Citrus (oranges, grapefruit, lemons)
• Stone fruits (peaches, plums, apricots)
• Mangoes and guavas
• Apples and pears
• Some vegetables including tomatoes and peppers

Texas maintains an aggressive eradication program in the Lower Rio Grande Valley, where Mexican fruit flies repeatedly enter from established populations in Mexico. The program employs multiple tactics including sterile insect releases, where millions of laboratory-reared, radiation-sterilized male flies are released to mate with wild females, producing no offspring. This technique gradually reduces wild populations without pesticides.

Quarantine regulations restrict movement of host fruits from infested areas to prevent spreading the pest to new regions. Growers in affected areas follow strict monitoring protocols, placing McPhail traps baited with attractants throughout orchards. When flies are detected, control measures intensify, including targeted insecticide applications, fruit stripping to remove host material, and enhanced sterile fly releases.

The Texas Department of Agriculture works closely with USDA Animal and Plant Health Inspection Service to coordinate responses. Residents in the Rio Grande Valley should not move homegrown citrus or other host fruits outside quarantine areas, as this can spread the pest to regions where it hasn’t established. Commercial growers participate in mandatory monitoring and control programs to maintain their ability to sell fruit outside quarantine zones.

5. Brown Marmorated Stink Bug

The brown marmorated stink bug (Halyomorpha halys) has established populations throughout Texas, feeding on hundreds of host plant species while seeking indoor shelter as temperatures decline. This shield-shaped invasive insect from Asia damages fruits, vegetables, and ornamental plants while creating nuisance problems when aggregating in homes.

Adults measure approximately five-eighths of an inch long with mottled brown coloring that provides effective camouflage. Distinctive features include white bands on antennae and alternating light-dark bands along the abdomen’s outer edges. They emit a characteristic foul odor when threatened or crushed, making them unmistakable once you encounter them indoors.

These stink bugs use piercing-sucking mouthparts to extract plant fluids, leaving behind dimpled or discolored areas on fruits and vegetables. Texas farmers report significant losses in orchards and vegetable gardens where bugs damage tomatoes, peppers, apples, peaches, and numerous other crops. On field crops, they cause poor seed quality in soybeans and corn while triggering secondary fungal outbreaks through feeding wounds.

1. Seal entry points before fall: Caulk cracks around windows, doors, and utility penetrations before late summer when bugs begin seeking winter shelter
2. Install or repair screens: Ensure all window and door screens fit tightly without tears or gaps
3. Remove indoor bugs carefully: Vacuum them and release outside rather than crushing, which releases defensive odor and stains
4. Use outdoor barrier treatments: Apply targeted insecticide treatments to building exteriors in late summer before aggregation begins

As temperatures decline in late summer and fall, brown marmorated stink bugs aggregate on south and west-facing walls, seeking entry through cracks and gaps. Once inside, they enter diapause—a dormant state—in attics, wall voids, and other protected spaces. They don’t reproduce indoors or cause structural damage, but large numbers create nuisance problems when they emerge on warm winter days or in spring.

Common Mistake: Many homeowners wait until stink bugs appear indoors to take action. Effective management requires prevention before fall invasion periods, as treating bugs already inside proves far more difficult than blocking entry.

Outdoor management for agricultural settings includes monitoring populations and applying insecticides when economic thresholds are reached. Natural enemies including parasitic wasps provide some biological control, though not enough to prevent economic damage in commercial settings. Research continues on improved management strategies, including attract-and-kill techniques and pheromone-based traps.

6. Sugarcane Aphid

The sugarcane aphid (Melanaphis sacchari) emerged as a devastating pest of sorghum across Texas beginning in 2013, causing yield losses exceeding 50% in untreated fields. This tiny invasive insect from the Old World tropics reproduces explosively, with populations capable of doubling every few days under favorable conditions.

Adult aphids measure only one-sixteenth inch long, appearing pale yellow to gray with dark leg joints and cornicles—the small tubes projecting from their rear. Unlike many aphid species, sugarcane aphids colonize the undersides of leaves throughout the plant canopy rather than concentrating on new growth. They reproduce asexually during most of the year, with females giving birth to live young without mating, enabling rapid population explosions.

Heavy infestations coat leaves with aphids and their sticky honeydew secretions, which promote sooty mold growth that interferes with photosynthesis. Severe infestations cause leaves to yellow, wilt, and die prematurely, reducing both grain yield and forage quality. Plants may lodge—fall over—due to weakening from aphid feeding and honeydew accumulation. The honeydew also gums up harvesting equipment, creating operational challenges.

Texas A&M AgriLife Extension entomologists recommend intensive scouting programs during sorghum production, checking plants weekly for aphid populations. Action thresholds vary by growth stage, with lower thresholds during critical periods like flowering and grain fill. When thresholds are exceeded, foliar insecticides provide effective control, though timing is critical—waiting too long allows populations to explode beyond manageable levels.

Natural enemies including lady beetles, lacewings, and parasitic wasps provide significant biological control when preserved. Avoiding broad-spectrum insecticides early in the season helps maintain beneficial insect populations that can suppress aphids below economic damage levels. Some sorghum hybrids show tolerance to aphid feeding, though no completely resistant varieties are currently available.

The aphid’s ability to survive year-round on volunteer sorghum and Johnsongrass creates continuous reservoirs for reinfesting new crops. Growers should destroy volunteer sorghum after harvest and control Johnsongrass in field margins to reduce carryover populations. Diversifying planting dates helps some fields escape peak aphid pressure, though this strategy proves less reliable as aphid populations have become established statewide.

7. Giant Reed Beetle

The giant reed beetle (Lilioceris cheni) arrived in Texas as an intentionally introduced biological control agent targeting giant reed (Arundo donax), one of the state’s most problematic invasive plants. This specialist beetle feeds exclusively on giant reed, making it valuable for managing this water-hogging plant that dominates riparian areas throughout Texas.

Adult beetles measure approximately one-quarter inch long with reddish-orange bodies and black heads, legs, and antennae. They feed on giant reed leaves, creating characteristic holes and skeletonization patterns. Larvae appear slug-like with dark coloring and feed on leaves while covered in their own excrement—a defensive strategy against predators. Both adults and larvae cause visible damage to giant reed plants.

Giant reed creates serious problems in Texas riparian ecosystems by forming dense monocultures along waterways, displacing native vegetation, and consuming enormous amounts of water through evapotranspiration. Studies in the Rio Grande Basin suggest giant reed uses significantly more water than native vegetation would, exacerbating water scarcity in this arid region. The plant also increases flood and fire risks while providing poor wildlife habitat compared to native species.

Important Note: The giant reed beetle represents an unusual case where an invasive insect provides environmental benefits by controlling an even more damaging invasive plant. Biological control programs require extensive research and regulatory approval before introduction.

Texas researchers monitor giant reed beetle populations to assess their effectiveness at suppressing giant reed growth and evaluate any unintended impacts. Early results show promise, with beetles establishing throughout much of the giant reed’s range in Texas and causing measurable reductions in plant vigor and water use. However, complete control requires integrated management combining beetle damage with other tactics including herbicides and mechanical removal.

The beetles naturally disperse along waterways, following giant reed populations without human assistance once established. Land managers working on giant reed control should avoid using broad-spectrum insecticides that would kill the beneficial beetles. Instead, they can combine beetle biological control with targeted herbicide applications or mechanical cutting to achieve better long-term management than any single tactic provides.

Water conservation benefits from successful giant reed control could prove substantial. Researchers estimate that replacing giant reed with native vegetation could conserve significant water resources in the Rio Grande Basin and other Texas river systems, providing economic value that justifies continued biological control efforts.

8. Tawny Crazy Ant

The tawny crazy ant (Nylanderia fulva), also known as the Rasberry crazy ant after the Texas exterminator who first documented it, has invaded areas along the Texas Gulf Coast from the Houston region to the Rio Grande Valley. These tiny reddish-brown ants measure only 2.4 millimeters long but form massive colonies with millions of workers that overwhelm native ant species and create unique problems.

The ants earn their “crazy” name from their rapid, erratic movement patterns rather than following straight trails like most ants. They don’t build visible mounds like fire ants but instead nest under objects, in wall voids, and in other protected spaces. Their populations can reach extraordinary densities, with millions of ants blanketing affected properties.

Tawny crazy ants create multiple serious problems:

• They displace native ants and other ground-dwelling insects, reducing biodiversity
• They climb into electrical equipment, causing shorts and failures
• They tend aphids and scale insects, protecting these plant pests from predators
• They invade homes in overwhelming numbers, contaminating food and living spaces
• They blind baby rabbits and other small animals by gathering around eyes and noses
• They lack the painful sting of fire ants but deliver annoying bites when disturbed

At Estero Llano Grande State Park in 2016, staff noticed the absence of local insects and reptiles after tawny crazy ant invasion, demonstrating their dramatic ecological impact. The ants form dense carpets on the ground and climb vegetation, trees, and structures, making affected areas difficult to use or enjoy.

Management options remain limited and challenging. The ants don’t respond well to traditional ant baits, and their massive colony sizes make control difficult. Texas A&M AgriLife Extension researchers continue studying management approaches, but no highly effective solutions have emerged. Property owners facing infestations often resort to repeated applications of contact insecticides around structures, though this provides only temporary relief.

The ants spread primarily through human-mediated movement of infested materials, equipment, or vehicles. People moving from infested to non-infested areas should carefully inspect items to avoid introducing the ants to new locations. As of recent surveys, tawny crazy ants remain concentrated along the Gulf Coast, though their ultimate range potential remains uncertain.

9. European Paper Wasp

The European paper wasp (Polistes dominula) has spread throughout Texas since its North American introduction, competing with native paper wasps while demonstrating more aggressive nest defense behavior. This social wasp builds distinctive umbrella-shaped paper nests from wood fiber mixed with saliva, suspending them from eaves, deck railings, and similar protected locations.

Adult European paper wasps measure approximately three-quarters of an inch long with distinctive yellow and black markings. Unlike native paper wasps that typically display more orange coloring, European paper wasps show brighter yellow patterns. They construct nests with visible hexagonal cells arranged in a single layer, usually gray or tan in color from the wood fiber used.

These wasps demonstrate more aggressive territorial behavior than many native species, stinging readily when they perceive threats to their colonies. Their venom causes painful stings that can trigger severe allergic reactions in sensitive individuals. Unlike honey bees that leave stingers behind, paper wasps retain their stingers and can sting multiple times, making encounters near nests particularly hazardous.

European paper wasps do provide benefits as predators of caterpillars and other soft-bodied insects that damage garden plants. They hunt actively, bringing paralyzed prey back to nests to feed developing larvae. However, their aggressive nest defense near doorways, play areas, or frequently used outdoor spaces creates safety concerns that often outweigh their beneficial aspects for homeowners.

Prevention strategies work best when implemented in early spring before queens establish new nests:

• Regularly inspect eaves, railings, and outdoor structures starting in March or April
• Remove small, developing nests immediately before colonies grow large
• Seal cracks and crevices where queens might overwinter or establish nests
• Paint or stain wooden structures to reduce suitable nesting surfaces
• Avoid wearing bright colors or floral perfumes near known wasp activity areas

Professional pest control services offer the safest removal option for established nests, particularly those in difficult-to-reach locations or near high-traffic areas. Attempting DIY nest removal can result in multiple stings when disturbed colonies swarm defensively. If removal is necessary, treat nests at dusk or dawn when wasps are less active and temperatures are cooler, wear protective clothing, and have an escape route planned.

10. Japanese Beetle

The Japanese beetle (Popillia japonica) feeds on more than 300 plant species, causing extensive damage to ornamental plants, fruit crops, and agricultural production in areas where it has established. While not yet as widespread in Texas as in states further east, monitoring for this invasive beetle remains important as its range continues expanding westward.

Adults display metallic green bodies with copper-brown wing covers, measuring approximately half an inch long. Five distinctive white hair tufts along each side of the abdomen and two additional tufts at the tip help distinguish them from native beetles. They aggregate when feeding, with pheromones attracting additional beetles to the same location and causing damage to escalate rapidly.

Pro Tip: Japanese beetle pheromone traps often attract more beetles than they capture, potentially increasing damage to nearby plants. Research shows that traps work better when placed away from valuable plants you’re trying to protect rather than right next to them.

The beetles create a characteristic skeletonized appearance on leaves, consuming tissue between veins and leaving only the framework behind. Heavily damaged plants show brown, lacy leaves that curl and drop prematurely. On fruits, beetles feed on ripe specimens, creating openings that allow disease organisms to enter. In agricultural settings, their damage weakens plants, reduces yields, and can kill younger or more vulnerable specimens.

Japanese beetles spend most of their annual life cycle as white, C-shaped grubs beneath the ground, feeding on grass roots and plant roots. They emerge in early summer to feed and mate for approximately three months before disappearing with fall’s arrival. This annual pattern makes control challenging, as both adult and larval stages require management for effective population suppression.

Management approaches include:

• Hand-picking beetles into soapy water, especially effective for small gardens
• Applying milky spore disease to lawns, which infects and kills grubs over time
• Using row covers or netting to protect high-value crops during peak beetle activity
• Planting less-preferred species near vulnerable plants as sacrificial trap crops
• Applying targeted insecticides to plants during peak adult feeding periods
• Treating soil with grub-control products before adults emerge

The beetles’ expansion pattern suggests Texas may see increased populations in coming years, particularly in areas with sufficient moisture to support their life cycle. Eastern and northeastern Texas appear most vulnerable to establishment, while drier western regions may prove less hospitable. Monitoring and early detection will prove critical for managing this pest before it becomes as established as in states like New Jersey and Ohio, where it causes tens of millions of dollars in damage annually.