March 2020
Invasive Tilapia Are Taking Over San Antonio Waters

There are apparently a lot of tilapia (Oreochromis aureus), a non-native species of fish, that have been taking over freshwater lakes and rivers in Texas, including Calaveras and Brauning Lakes in San Antonio. In Texas, tilapia should be gutted almost immediately because it is unlawful to transport or possess a live fish, or to release tilapia back into the lakes. An angler could receive a ticket if caught. Learn more at

Blue Tilapia
Credit: Michael Rupert Hayes, Wikipedia, CC BY-SA 2.0

Zebra Mussels Found in First West Texas Reservoir

In a news release, the Texas Parks and Wildlife Department (TPWD) has announced that it has added O.H. Ivie Lake near San Angelo to the statewide list of lakes designated as "positive" for invasive zebra mussels (Dreissena polymorpha). Lakes are designated as "positive" when zebra mussels or their larvae have been detected on more than one occasion, but there is no evidence of a reproducing population yet.

"O.H. Ivie is now the sixth lake in the Colorado River Basin with invasive zebra mussels... Because O.H Ivie is miles upstream of where they have been found before in the river basin, it is likely they were transported to the lake on a boat or other equipment."

If you find zebra mussels at O.H. Ivie, or in lakes where they aren't known to occur, please immediately report your sighting to TPWD by emailing photos and location information to, calling (512) 389-4848, or by submitting a report and photo to the Sentinel Pest Network.

As of March 2020, zebra mussels are found in 30 Texas lakes across five river basins. A status map and full list of these lakes can be found on the TPWD zebra mussel website, and at

zebra mussels
Credit: Amy Benson, U.S. Geological Survey,

Lake O.H. Ivie
Credit: Texas Water Development Board

Annual Inter-Agency Giant Salvinia Taskforce Conference Held in Oil City, LA

In early February, Caddo Lake Institute and the Inter-Agency Giant Salvinia Taskforce (IGGST) brought together experts from 4 states, 2 federal agencies and local government officials to share their latest information on and techniques for managing Giant Salvinia (Salvinia molesta). Some topics of discussion were prevention, containment booms and the latest in herbicide and biocontrol measures. John Findeisen with TPWD, Dr. Chris Mudge with the LSUAg Center, and Dr. Mark Weaver with the USDA Bio Control of Pests Research Unit were just a few of the experts in attendance to discuss this invasive species. The consensus among the specialists is that managing Salvinia requires more than one facet: prevention, (where possible), containment, herbicides, and biological agents are all needed to combat this tough invasive. This annual meeting is part of Caddo Lake Institute’s efforts to manage invasive species by sharing the latest information with those affected by Giant Salvinia or other invasives. The day before, members of the Weevil Rearing Working Group and others attended a meeting in Uncertain, TX, to discuss the rearing of salvinia weevils (Cyrtobagous salviniae) at Caddo Biocontrol Alliance's rearing facility.

IAGST Meeting Feb 11 2020
The IAGST meeting in the Louisiana State Oil and Gas Museum in Oil City, LA. Credit: Laura-Ashley Overdyke, Caddo Lake Institute

Giant Salvina Rearing Working Group meeting in Uncertain TX 2-10-2020
The Giant Salvinia Weevil Rearing Working Group meeting at the Caddo Biocontrol Alliance's Morley Hudson rearing facility in Uncertain, TX. Credit: Hattie Lee Hackler, Caddo Biocontrol Alliance

Pablo Escobar's Hippos Illustrate Controversial Ideas About "Rewilding"

"Rewilding" has many meanings (see abstract of Rewilding: Science, Practice, and Politics (2015), by J. Lorimer et al.), but you can think of it as reintroducing a species to an area where it had been extirpated, such as reintroducing the grey wolf (Canis lupus) to Yellowstone National Park, or introducing a non-native species to take the place of an extinct species to help the ecosystem recover former function lost due to that extinction. A new study published in the Proceedings of the National Academy of Sciences (link to abstract) by an international group of researchers examines the latter case for large herbivores. They argue that what most conservation biologists and ecologists think of as the modern 'natural' world is very different from what it was for the last 45 million years during the Late Pleistocene (LP), when large animals such as glyptodonts, giant ground sloths, flat-headed peccaries, and giant llamas roamed. They compared living large herbivores from around the world to extinct ones to determine whether introduced herbivores "restore – or contribute novel – functions relative to LP assemblages." The researchers found that introductions – "rewildings" – can in fact restore many important ecological traits that had been lost since the LP.

You may have seen news items about this research in reference to the hippos (Hippopotamus amphibius) that Pablo Escobar had in Columbia – for example, this one is from

"When cocaine kingpin Pablo Escobar was shot dead in 1993, the four hippos he brought to his private zoo in Colombia were left behind in a pond on his ranch. Since then, their numbers have grown to an estimated 80-100, and the giant herbivores have made their way into the country's rivers. Scientists and the public alike have viewed Escobar's hippos as invasive pests that by no rights should run wild on the South American continent. A new study … challenges this view."

The research illustrates two aspects of the controversy about rewildings. First, it brings to the fore the question in restoration and conservation ecology about what state are restoration or conservation efforts trying to restore to or conserve? In this case, do we want to restore an area to what it looked like during the LP? Why not restore it to an even earlier state? What is a "natural state"? Second, what are we trying to restore or conserve: ecological function, biodiversity, or former community assemblages? If ecological function, do we use non-native species as tools to restore that function?

So, do the results from the study by J. Lorimer et al. argue for returning to the LP, and using non-native large herbivores to get there? What do YOU think? (The researchers don't necessarily argue for a certain policy, only that their results contribute to the discussion.)

Read more about the impacts of Pablo Escobar's hippos at


Glyptodonts. Credit: dinopedia

compare North and South American extinct & extant large herbivores
Introduced herbivores share many key ecological traits with extinct species across the world. Credit: University of Kansas/Oscar Sanisidro (from

Students Use Invasive Species to Create Environmentally Friendly Hair Product for Black Women

Two science graduate students from the University of Michigan have started a company to produce biodegradable braiding hair made from phragmites (Phragmites australis), an invasive plant species. Jannice Newson and Nana Britwum founded the company, whose slogan is "Hair without harm."

"That means no harm to women who use braiding hair and no harm to the environment," Newson says.

As this article reports, "Inspiration came from the duo's own unpleasant experiences with synthetic braiding hair. They both dislike how the plastic-based hair currently on the market is itchy, painful, heavy, and unhealthy. And both are troubled that discarded synthetic braiding hair contributes to pollution in landfills and oceans.

"'Now we're not just making a product for me and Jannice to wear for fun,' Britwum says. 'We're making something that our friends and family can use and that millions of black women across the world can use.'"

"A prototype is currently in development with a soft launch date projected for this fall. The goal is plant-based hair that is much lighter than synthetic hair and doesn't have the chemical coating found on plastic hair.

"'It's the chemical coating that causes scalp and skin irritation, and we're eliminating that,' Newson says. 'But our hair will still have all the qualities that people desire from plastic hair, plus it can be worn for an extended time.'"

Credit: Michigan State University Extension

hair braiding extensions

Most Bird Feed Contains Troublesome Weed Seeds

Many millions of homeowners use feeders to attract birds. But a two-year study suggests there may be one unintended consequence of this popular hobby. Bird feed mixtures may be helping to spread troublesome weeds that threaten agricultural crops.

Researchers examined the contents of 98 commercially available bird feed mixes and found, among other things: seeds from 29 weed species including pigweed species (Amaranthus spp.), kochia (Bassia scoparia), common ragweed (Ambrosia artemisiifolia), foxtail species (Setaria spp.) and wild buckwheat (Fallopia convolvulus), among others [Note: not all the species are non-native]; 96 percent of the mixes contained seeds for pigweed species weeds (which can represent a significant threat to agriculture); some plants germinated from the seed in greenhouses exhibited resistance to glyphosate; and that there was a correlation between the presence of some of the bird feed seed species and some of the weed species.

The researchers also recommended various ways to mitigate the risks of contamination of birdseed.

Learn more at


North American Invasive Species Management Association Training Webinars

The 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.

NAISMA 2020 Webinar Schedule; webinar links will be coming soon.

  • May 20 – Kurt Dreisilker, Morton Arboretum: How the Morton Arboretum approaches invasive species prevention and EDRR – REGISTER
  • June 17 – Forest Eidbo, Minnesota DNR: Making educational signage that people actually read, according to the experts – REGISTER
  • July 15 – Gary Lovett, Cary Institute of Ecosystem Science: Invasive forest pests in the U.S.: Impacts and policy solutions – REGISTER
  • August 19 – How biocontrol agents are approved and how to access them for your invasive species management needs (go to NAISMA 2020 Webinar Schedule page to register.
  • September 16 – Leaps and Bounds – How to jump over the barriers to preventing the spread of invasive species – REGISTER

Earth Month Webinars

All webinars are open to the public.
Join them every Wednesday from 1:00 p.m. – 2:00 p.m. Central Time during the month of April for a special webinar series to support your professional development.

  • April 1: The Green Pathway to Invasive: Ornamental Invasive Plants – REGISTER
  • April 8: What's That Smell? The Curious Case of the Callery Pear – REGISTER
  • April 15: Invasive Bark and Ambrosia Beetles: Their Impacts and Detection – REGISTER
  • April 22: EDDMapS 2020: Integrated Platform and Program for Tracking Invasive Species Management in North America – REGISTER
  • April 29: Eyes in the Sky: Leveraging New Remote Sensing Technologies to Detect Invasion at a Distance – REGISTER


Invasive Spotlight:
Cuban Tree Frog
(Osteopilus septentrionalis)

The following information is modified from the University of Florida Florida Extension Wildlife webpage on the Cuban treefrog.

The largest tree frog in North America is the Cuban tree frog (1.5 to 5 inches in body length), but it is not native to North America. It causes ecological problems as a predator of a wide range of native frogs, toads, and lizards, in addition to insects and spiders. This species was introduced to southern Florida from the Caribbean and has continued to spread. There is a breeding population in New Orleans, and they have been found in Texas! It is very important that those of you in the Houston area and along the coast from the Texas-Louisiana border to past Galveston keep an eye and ear out for these frogs.

Description: The distinguishing characteristics of the Cuban tree frog are:

  • Size of the adults (up to 5 inches in body length, much larger than native Texas tree frogs);
  • Enormous toe pads (larger than toe pads of native tree frogs in Texas), as large as its eardrum;
  • Bumpy skin on the back, like skin of a toad; and
  • Skin on top of head is fused to skull. A good test to determine if a frog is a Cuban tree frog is to grasp the frog firmly, but gently, and try to move the skin around on the top of the frog's head with your fingertip. Because the skin on the head of a Cuban tree frog is fused to the top of the skull, it won't move.

Cuban tree frogs can be highly variable in color — from pale tan/pale green without any markings to dark green or brown with an even darker color pattern on the back and legs. Sometimes they almost look white when they are inactive or cold. The Florida Extension Wildlife page on the Cuban treefrog has photos that illustrate this variability.

Wear gloves or put your hand in a plastic bag when handling the Cuban tree frog. They secrete a slimy film to protect their skin, which can irritate the skin and eyes of some people.

Habitat: This species prefers habitat that is moist and shady — in trees, shrubs or around houses. It is commonly found near ornamental fishponds and well-lit patios.

Reproduction: The breeding season lasts from May to October. The voice, or call, of the Cuban tree frog is variably pitched, slightly rasping or like grating stone.

To listen to the call of the Cuban tree frog, click HERE and select "Cuban tree frog" from the dropdown list for Common Name, and click on the "submit" button.

Here is a flyer from Louisiana describing the Cuban treefrog. An excellent, extensive and informative web page from Louisiana is here.

If you think you found a Cuban tree frog, please collect it if possible (using gloves) and report it to the USGS and to (put "Cuban tree frog" in the subject line, take up to 4 photos to submit and/or include a description, and include the location.

Cuban Treefrog

Note large toe pads. Credit: Leanna Powers

cuban tree frog

Example of color variation. Note large toe pads and rough skin on the back, Credit: Denise Gregoire, U.S. Geological Survey

treefrog toepads

Source: Comparison between the size of toe pads of native tree frogs and the Cuban tree frog. Credit: Monica McGaritty, TPWD


More News

7 Invasive Animals That Have Wreaked Havoc in the US
This short article on the History Channel's website describes the impacts that five invasive animal species have had and continue to have. The species are feral swine (Sus scrofa), Burmese python (Python bivittatus), domestic cats (Felis catus), European starlings (Sturnus vulgaris), nutria (Myocastor coypus), Asian carp (multiple species), and gypsy moths (Lymantria dispar).

Impact of Zebra Mussels Infesting NY Trout Hatchery
The recent discovery of zebra mussels (Dreissena polymorpha) earlier this month at one of New York state’s fish hatcheries means reduced or possibly no stocking of trout this spring in parts of the Adirondacks and Central New York. In addition, the entire hatchery will have to be decontaminated, redesigned and reconstructed. Read more at

NMMA Hosts Aquatic Invasive Species Event on Capitol Hill
The National Marine Manufacturers Association (NMMA), in coordination with the Congressional Boating Caucus (CBC), hosted a briefing event in late February for nearly 50 congressional staff in Washington, D.C. to examine the role Congress can play in combating aquatic invasive species (AIS). Learn more at the NMMA website.

2020 Asian Carp Action Plan Released
The Asian Carp Regional Coordinating Committee has released its 2020 Asian Carp Action Plan. "The updated Action Plan includes aggressive new prevention and control efforts, including expanded Asian carp population reduction efforts, large-scale field trials of potential barriers and deterrent technologies, and actions to address black and grass carp threats." Visit to read the complete announcement and learn more.

A Novel Tool for Managing Asian Carp?
New research is exploring using DNA editing techniques to create male zebrafish (Danio rerio) that produce seminal fluid that would destroy the eggs of females during spawning, targeting only that species. Success would lead to attempting to use the technique with Asian carp, which could be applicable to other invasive species. Learn more at

Invasive Mussel News from the West
New Mexico has managed to keep invasive aquatic mussels out – a tough task with nearby Lake Powell infested with mussels. Meanwhile, the U.S. Department of the Interior announced that four of its Bureaus will further coordinate efforts to prevent, contain and control quagga (Dreissena bugensis) and zebra mussels (D. polymorpha) in waterways across the Lower Colorado River Basin.

Salamanders Under Threat of Non-native Fungal Pathogen
North American salamander species are facing a fungal pathogen called Bsal that may wipe out a third of their population. Currently in Europe, this pathogen will likely spread to America. Researchers are working to understand the threat to help protect wildlife and help prevent what could be a tremendous loss in biodiversity. Learn more at

Sea Urchins Helping to Control Invasive Seaweed in Hawai'i
Building on the success of releases of collector urchins (Tripneustes gratilla) to control invasive seaweed in Kane‘ohe Bay over nine years, hatchery-raised native sea urchins are now being released in another area. Read more at

New Method for Determining Where to Focus Invasive Species Management Efforts in South Africa
Researchers in South Africa combined census data and information on invasive plants to prioritize localities for invasive species management by determining where people are most impacted. The poorest communities typically were most affected by invasive plants. Read more at


If you would like to highlight a successful invasive species project or nominate a special person to be highlighted in an upcoming iWire, please send the details to

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, and teach identification of local invasive plants, and to 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:

  --- None scheduled.

For more information or to register to attend a free workshop, please visit the Workshop Page.