December 2023
Extras in your Evergreen

You're probably familiar with the partridge in a pear tree, but what about western yellowjackets in your Christmas tree?

There have been multiple reports of Christmas trees being transported while carrying live cargo, some of which turn out to be invasive species. This can quickly become detrimental as coniferous evergreen trees (family Picaceae) are imported and exported all over the world. For example, more than 95% of evergreens imported from Canada are sent to the U.S., while others are sent to areas such as Panama, different Caribbean countries, Venezuela, or the United Arab Territories.

In order to reduce the importation of pests or other living hitchhikers, agricultural inspectors, with the port authority, inspect each shipment and/or shipping container. This is done by shaking a certain portion of trees, either mechanically or by hand, before and after shipping. From there, shipments can be deemed ‘low risk’ and released, sent back to the shipper, or held for quarantine and treatment before release. Those held in quarantine require treatment either by shaking 100% of the trees or by hot-water treatments (most often used for slug infestations). For an example of how the Hawaii Department of Agriculture handles evergreen shipments, click here.

One non-profit organization who focuses on science-based solutions for agriculture and the environment, called the Centre for Agricultural Biosciences International, has put together a list of 12 common Christmas tree hitchhikers, such as the green spruce aphid (Elatobium abietinum), spruce beetle (Dendroctonus rufipennis), silver fir adelges (Dreyfusia nordmannianae), and more. This is not an all-inclusive list. Garter snakes, rat lungworm parasite carrying slugs and snails, blights, and fungi have also been introduced accidently via the transportation of coniferous evergreen. At least two strains of invasive western yellowjackets are believed to have been introduced to Hawaii from Christmas trees imported from Oregon. Another pest of grave concern is the spongy moth (Lymantria dispar). The presence of this invasive has caused the shutdown of multiple Christmas tree lots in Canada over the years.

The inside of your house is not a hospitable habitat for many of these hitchhiking pests. However, a lot can happen before your tree is placed before the hearth. Authorities encourage everyone to purchase their Christmas trees locally if it’s possible. Otherwise, they recommend that you give your tree a good shake over a clear solid surface (such as your driveway), to dislodge any critters that may have been a bonus with your tree purchase. Anything that falls out should be smashed/killed. Please, do not spray any aerosol pesticides on your Christmas tree – they are highly flammable!

Read more about Christmas trees that have the potential to spread unwanted critters.



 group of trees copyEvergreens. Credit: National Archives and Records Administration, Public Domain.

xmas tree frog copyPacific Chorus frog (Pseudacris regilla) found in a Christmas tree being sold in Anchorage, Alaska. Credit: Stephen E. Clark, Alaska Department of Fish & Game via AP.

xmas tree hemlock scaleA closeup of elongate hemlock scale (Fiorinia externa), a tiny insect found on many wreaths and other holiday decorations sold at big box stores across Wisconsin. Credit: Vermont Invasives photo.


Anchors Aweigh

Zebra mussel (Dreissena polymorpha) contribute to biofouling along all kinds of surfaces. They have been found growing along piers, beaches, rock beds, and just about any available surface they choose fit in a freshwater habitat. They are causing irreversible damage to historically important sunken discoveries. They can grow so dense, they obstruct pipelines, which can be additionally problematic and costly near power stations and water treatment plants. These invasive mussels are most commonly spread via boats, ship motors, anchors, and ballast water. They have even snuck their way into mossballs and moss packages sold in pet stores. Once introduced, their ability to anchor to surfaces is one of the things that makes these mussels seem infallible. Fortunately, a study that is looking into the details behind zebra mussel’s adhesive abilities may have some new insights.

A recent discovery has provided an explanation to the evolutionary occurrence that has enabled zebra mussels to become so globally widespread and harmful. It turns out that a bacterium transferred a single gene precursor to a single mussel 12 million years ago which provided each descendant thereafter with the ability to make protein-based fibers, called byssus threads, that allows them to anchor onto surfaces. Researchers believe this horizontal gene transfer event supported the resilience of this species. They believe this knowledge could help level the playing field and improve future strategies against biofouling.

This study also described how this discovery could be used to develop mussel fiber into sustainable material. Dreissenid byssus fibers were found to structurally resemble spider silk. Therefore, the researchers believe it could be used to develop polymer fibers, which could contribute to tougher, more durable, sustainable materials in the future. The biotechnological manufacture of sustainable fibers is an industry currently dominated by artificial spider silks. The fiber fabrication methods and processing required for Dreissenid byssus fibers is simpler than those required for spider silk. This could provide a new means for manufacturing more sustainable plastics and textiles.

Read the research: Simmons et al., 2023
*link contains a video of a zebra mussel producing a byssus thread.

Byssal threads copy
Zebra mussel (Dreissena polymorpha) with visible byssus threads. Credit: Harrington et al., 2010.

pipe clogged with zebra mussels
Example of pipe clogged with zebra mussels. Credit: Craig Czarnecki, Michigan Sea Grant,

native clam (Amblema plicata) with the zebra mussels attached to it
Native clam (Amblema plicata) with the zebra mussels attached to it. Credit: Randy Westbrooks, Invasive Plant Control, Inc.,

Citrus In Your Backyard!

The Asian citrus psyllid (Diaphorina citri) and the Citrus Greening pathogen (Candidatus liberibacter asiaticus) are threatening citrus in multiple Texas counties, and we need your help to collect samples to monitor the spread to ensure that you and your neighbors are not affected. This pest and pathogen are extremely detrimental to Texas citrus, both economically and agriculturally. The presence of either can greatly affect citrus yield.

TISI is offering FREE diagnostic services! If you suspect your citrus has either the psyllid pest or the Citrus Greening pathogen, or you would like your citrus plants to be part of our screening survey, contact

We will send you all the instructions you will need. If you are located within 200 miles of our headquarters, we can collect samples, and/or provide traps and monitoring services ourselves. Not only will we share the results and management strategies (where applicable), but you will become part of a multi-county monitoring survey that is striving to improve the health of Texas citrus!

Also Available: TISI offers educational workshops that highlight information about the Asian citrus psyllid, the pathogen Citrus Greening, and what you need to look out for in your own backyard. If you are interested in this, TISI will provide trapping materials, assist with management strategies, and more. Don’t waste another second. Help us stop the spread!

symptoms of citrus greening. Jeffrey W. Lotz. Florida Department of Agriculture and Consumer Services.
Symptoms of citrus greening bacterium. Credit: Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services,

citrus greening
Leaf mottle on grapefruit, a characteristic symptom caused by citrus greening bacterium but also seen on trees infected by Spiroplasma citri. Credit: J.M. Bove.

Self-Cloning Invasive Crayfish

Texas Parks and Wildlife is warning Texans of the possibility of a self-cloning invasive species called the marbled crayfish (Procambarus virginalis). This aquatic invasive is a popular pet store purchase for aquarium owners. Authorities made a special social media post to remind the public to Never Dump Your Aquarium into natural bodies of water or flush them down the toilet because it contributes to invasive species introduction. The marbled crayfish could be particularly damaging to Texas ecosystems if it were to be introduced.

All individuals within this species are females and reproduce through cloning. A single individual alone can start a population with the ability to lay up to 700 unfertilized eggs that develop into genetically identical offspring. The marbled crayfish ranges between 4-5 inches in length and ranges from olive green to dark brown, or tan to reddish to blue. These crayfish are banned all over the world, including five U.S. states (Idaho, Maryland, Michigan, Missouri, and Tennessee). To reiterate, these crayfish are not naturally found in Texas and have not yet been recorded as an invasive caught in the wild. However, they are widely available in pet stores and in the aquarium trade, which creates a high risk of introduction.

TPWD reminds everyone to "Never release aquarium life and learn before you buy!"


marble crayfish. facebook
Marbled crayfish (Procambarus virginalis). Credit: TPWD

Port Aransas Releases Biocontrol

The Brazilian peppertree (Schinus terebinthifolia) covers thousands of acres along the southern coast of Texas. Each small tree sprouts from multiple trunks and forms a dense thicket of twisting branches that chokes out native vegetation and can cause an allergic reaction in people. Usually, mitigation includes manual cutting, herbicide, and control burns. However, a species-specific biocontrol has recently been approved for release to aid in the control against Brazilian peppertree, called the Brazilian peppertree thrips (Pseudophilothrips ichini).

Texas Gulf Region CWMA (Cooperative Weed Management Area) in Port Aransas joined forces with Texas A&M Forest Service and other affiliations (see list below*) several years ago to fight back against these spreading invasive trees. Through these collaborative efforts, CWMA was recently able to receive funding for a Brazilian peppertree biocontrol project (funded by USFS, Biological Control of Invasive Forest Pests Grant). Brazilian peppertree thrips have been introduced to 28 plots across Port Aransas. The goal of the study is to not only observe the success of the biocontrol, but to study its effectiveness and compatibility when integrated with the ongoing mitigation efforts, i.e. mechanical and herbicide management. Researchers plan to release new insects and monitor the trees over a two-year period to evaluate the impact. At the end of the two-year period, the Brazilian peppertree population within the management areas will be cross examined, comparing current to past.

*Other affiliations: the US Army Engineer Research and Development Center, the University of Texas Marine Science Institute and the City of Port Aransas.

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Brazilian peppertree thrips (Pseudophilothrips ichini). Credit: CWMA
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Researcher examining biocontrol damage on Brazilian peppertree(Schinus terebinthifolia) in one of the study areas. Credit: CWMA

North American Invasive Species Management Association Training Webinars

This program is designed to provide the education needed for professionals and students who are managing or learning to manage invasive species. The courses include the most current invasive species identification, control, and management techniques, and how to comply with local and federal regulations.

Participants may register and enroll at any time, and will receive a certificate of invasive species management from NAISMA upon completion of the program.

All live webinars are open to the public. Recorded webinars are available to members of NAISMA.

NAISMA 2020 Webinar Schedule:

  • January 17, 1pm CDT- Protecting Threatened and Endangered Species from Pesticides. REGISTER.
  • February 26, 1pm CDT- Annual USGS Invasive Species Research Forum. REGISTER.
  • February 28, 1pm CST- The Federal Interagency Committee on the Management of Noxious and Exotic Weeds. REGISTER.
  • February 29, 1pm CST- Opportunities and Challenges for Preventing the Next Plant Invasion. REGISTER.



Invasive Spotlight:

Turkestan Cockroach
(Blatta lateralis)

Turkestan cockroaches (Blatta lateralis) are 15-28mm in length and are commonly found around household water meters and sewers. These cockroaches display a color variation between males and females. Males are red-brown with pale to white lateral stripes on the lateral sides of the wing base. Adult females are dark brown with short lateral white dashes at the end of the wing. Male wings extent to cover the full abdomen, while female wings are very short, leaving some of the abdomen exposed. Each female produces egg capsules, or ootheca, that are 3/8 inch long, dark brown in color, and contain about 18 eggs each. The nymphs are small with short wing buds, a light brown thorax, and dark brown abdomen. These are recorded as being very rapid breeders.

Turkestan Cockroach can be found in a variety of habitats, such as semi-arid and arid deserts, and urban areas, such as water meter boxes, compost piles, leaf litter, potted plants, sewer systems, and cracks in concrete walkways. As a possible vector of diseases, they present an ecological threat through water contamination and spread of diseases through their presence in sewer systems. They are also known to damage household plants and crops by over feeding.

Male Turkestan cockroaches are often mistaken for American cockroaches (Periplaneta americana) and females are similar in appearance to oriental cockroaches (Blatta orientalis). One way to help tell them apart without getting too close (for those that don’t like cockroaches) is based on behavior. Turkestan cockroaches can fly and jump but cannot climb. Oriental cockroaches cannot fly. American cockroaches can do it all.

Once a colony of Turkestan cockroaches is established, they can be very difficult to control or eradicate due to their ability to breed and reproduce quickly. These cockroaches have been reported in much of the southwest region of the U.S., spanning from Southern California to Texas. They are believed to have been spread to the U.S. with military troops returning from the Middle East in the 70s. If you believe you have found a Turkestan cockroach, please email a picture and the location to here. For more details or management information, see the species page.

Blatta lateralis mating. Happy 1892 CC BY-SA 3.0 
Turkestan cockroach (Blatta lateralis) male and female mating. Note the differentiation of wing length between the sexes and white lines on lateral sides of wings. Credit: Happy1892, CC BY-SA 3.0
Blatta lateralis ootheca. Happy1892 CC BY-SA 3.0
Turkestan cockroach ootheca. Credit: Happy1892, CC BY-SA 3.0

Turkistan Roach nymph. Happy 1892 CC BY-SA 3.0
Turkestan cockroach nymph. Credit: Happy1892, CC BY-SA 3.0

Get Involved Today!!

The Texas Invasive Species Institute (TISI) and The Texas Research Institute for Environmental Studies (TRIES) have many surveys and projects underway. These facilities strive to provide yearly invasive species presence and absence data to the authorities. Pre-screening is one of the first lines of defense in the war against invasives. However, sometimes it is hard to do it alone.

With the aid of the public and citizen scientists, we could cover a much wider area, and gather a more substantial amount of data. When it comes to protecting our environment, there is an opportunity for everyone! Together we can make a difference, one research project at a time.

See how you can get involved by reading the projects listed below or see all the available projects on the Texas Invasives website HERE.


Air Potato Survey

Help Texas Research Institute for Environmental Studies conduct an air potato survey by actively reporting any infestations seen in your area. The air potato (Dioscorea bulbifera) is a fast growing, high climbing vine. Potato-like tubers are the primary means of reproduction for this vine. They can be as small as a marble or as large as a softball. Native yams are often confused for air potatoes. To avoid this confusion, please refer to the key below:

- Plants rhizomatous; bulbils never produced in leaf axils; petiole base never clasping the stem; Native D. villosa
- Plants tuberous; bulbils produced in leaf axils; petiole base sometimes clasping the stem; Invasive D. bulbifera

For additional information, please refer to the TexasInvasives information page.

If you believe you have identified an air potato vine, please email and include the following information: an image, an approximate number of vines present, the location (including whether it is on public or private land), and if bulbils are present (the potato-like tubers that emerge from the stem).

Participation opportunities

Participation Opportunities. Credit: KNKleiner, TRIES.


air-potato (Dioscorea bulbifera)2 bulbil. credit Karen Brown

Air-potato (Dioscorea bulbifera), bulbil emerging from leaf axil. Credit: Karen Brown.  

Video Invasion

Monthly video picks about invasive species or the people that want to tell us more about them. There are some amazing citizens and professionals around the world that poke, prod, chase, dive, and investigate everything they can about these alien invaders. Jump into this cinematic rabbit hole. You never know what you may learn.

New Report Sheds Light on Environmental, Financial Costs of Invasive Species. PBS Newshour.

Invasive species harm ecosystems around the world and cost the global economy $423 billion a year, according to a UN report. However, researchers believe this may be an underestimate. A PBS journalist speaks with a researcher about the ways invasive species affect us and how this estimate could be wrong.

Lab-Raised Bugs Used to Combat Invasive Species. CBS Evening News.

CBS journalist looks inside the Palestine Insectary in Colorado. This lab raises biological controls aimed to kill invasive insects and plants, such as tamarisk leaf beetles (Diorhabda carinulata) which target invasive tamarisk plants (Tamarix chinensis and T. ramosissima), or small parasitic braconid wasps, nicknamed MAC (Macrocentrus ansylivorus) which kill agriculturally detrimental peach moths (Grapholita molesta). The release of these biological control agents offers a pesticide free alternative when fighting invasive infestations.

How Invasive Species Spread Across the U.S. Pestworld.

The brown marmorated stink bugs (Halyomorpha halys), formosan termites (Coptotermes formosanus), spotted lanternflies (Lycorma delicatula), and more… Where did they come from? How did they get to the U.S? How did they get to your home? See how these pests trek cross country before they make it to your front door. As a bonus, there are many additional interesting invasive species videos below this one available for viewing. They cover a wide range of topics, from the northern giant hornet (Vespa mandarinia) to the Asian longhorn tick (Haemaphysalis longicornis).

More News

These Invasive Plants Found in West Texas Are Bad News
A quick read about four invasive plants found in west Texas.

Waterfowl Hunters Play Major Role in Helping Prevent Spread of Invasives
TPWD reminds hunters across the state to join the fight against the spread of aquatic invasive species and be vigilant during waterfowl season. Hunters play an important role in preventing the spread of aquatic invasives by keeping hunting gear and boats clear of hitchhikers as they move from lake to lake.

Arlington Parks And Recreation Wins Pair of Region Awards
Arlington’s GLOW (Growing Leaders in Outdoor Wilderness) Girls won the 2023 TRAPS North Lone Star Programming award, and The Friends of Arlington’s Unique Natural Areas (FAUNA) was named Advocate of the Year by the TRAPS North Region.

'Plant Magic' Uses Native Plants to Draw Out Natural Beauty
Owner of a gardening company that strives to educate people about invasive people, provide garden maintenance, and encourage the growth of native species.

Google Weed View? Professor Trains Computer to Spot Invasive Weed
Using artificial intelligence and machine learning, UC Davis researchers have developed a way to use photos from Google’s Street View database to track down various invasive species in a fraction of time and for a fraction of the cost it takes to survey in person.

An Invasive Tick That Can Clone Itself Is Spreading Across the U.S., Threatening Livestock
The Asian long horned tick (Haemaphysalis longicornis) has been spreading across the eastern U.S. These ticks pose a serious threat to livestock because they congregate in the thousands and can drain an entire animal of blood.

Harvey Norman Bed Discovered Riddled with Invasive Species from China
A woman from Tasmania was alarmed to find that her new Harvey Norman bed arrived with several unknown insects. She alerted her local biosecurity agency, who soon determined they were dealing with invasive China fir boring beetles (Semanotus sinoauster).

Ronan Middle School Drone Club Soars to New Heights
A group of middle school children described a project where they coordinated with tribal lands and used drones to help identify invasive plant species in an effort to help agriculture and native plants.

Study Identifies Florida's Potential Invasive Species Threats
To save Florida’s natural areas, researchers have compiled a list of invasive species that pose the greatest threat. Each species on the list is given a score based on several different attributes from likelihood of arrival to human health impact.

New Study Highlights Invasive Rodent Attacks on Sand Island Bird Species
A new study not only examines how invasive mice affect nesting mōlī (Laysan Albatross), but provides a comprehensive analysis of how these rodents affect the Sand Island ecosystem.

Sentinel Pest Network and Invaders of Texas Workshops

Invaders of Texas workshops train volunteers to detect and report invasive species as citizen scientists. Workshops, which are free, are designed to introduce participants to invasive species and the problems they cause, cover aspects of invasive species management, teach identification of local invasive plants, and train participants to report invasive plants using the TX Invaders mobile application. The workshop is 7 hours long (usually on a Saturday, but scheduling is arranged with each individual host group). The workshop satisfies Master Naturalist training requirements.

Sentinel Pest Network workshops serve to increase the awareness and early detection of a set of particularly important invasive species to help prevent their spread into Texas or their further spread within Texas. Participants learn to identify species such as the Emerald Ash Borer, Cactus Moth, Asian Longhorned Beetle, and other pests of regulatory significance, and to report them. The workshop is 3.5 hours long. The workshop satisfies Master Naturalist training requirements.

Upcoming Workshops:

Invasive Species Presentation, Kyle Garden Club
January 9th, 2024
Time: 10:00-11:30 am
Kyle Methodist Church
Contact: Glenda Conley (

Meeting with Galveston Bay Estuary Program Council
Discussion with local partners and entities to show what Texas Invasives provides and how we can support one another’s programs in the future.
January 17th, 2024
Time: 9:30am-12:30pm
Harris-Galveston Subsidence, District, Friendswood, TX

Citizen Scientist Training, Woodlands Invasive Species Task Force
February 17th, 2024
Time: 8:30-12:30pm
Woodlands Emergency Training Center, 16135 Interstate 45 S, Conroe, TX 77385 Contact: Terrilyn MacArthur (

Invasive Species Presentation, Burnet Master Gardeners
February 28th, 2024
Time: 12:30-2:30pm
Marble Falls, TX
Contact: Joan Altobelli

CITRUS WORKSHOPS: Stay tuned for upcoming 2023 virtual weekend presentations about Citrus diseases and FREE testing we offer at Texas Invasive Species Institute.