The Asian Invasion: Stink Bug, Asian Carp, Northern Snakehead Fish and Burmese Python

The brown marmorated stink bug is known as an agricultural pest in its native range of China, Japan, Korea and Taiwan. Recently, it has become a serious pest of fruit, vegetables and farm crops in the Mid-Atlantic region, and it is probable that it will become a pest of these commodities in other areas of the United States. - Brown Marmorated Stink Bug, Penn State College of Agricultural Studies, September 2010

Stink Bugs Causing Crop Damage in the United States

The Washington Post
September 24, 2010

Shaped like shields and armed with an odor, dime-size brown bugs are crawling into area homes over windowsills, through door crevices and between attic vents in such numbers that homeowners talk about drowning them in jars of soapy water, suffocating them in plastic bags or even burning them with propane torches. In the process, some people are unwittingly creating another problem: When squashed or irritated, the bugs release the distinctive smell of sweaty feet.

Get used to it, experts say -- the invasion is only going to get worse.

"This is the vanguard," said Mike Raupp, a University of Maryland entomologist and extension specialist. "I think this is going to be biblical this year," he said. "You're going to hear a collective wail in the Washington area, up through Frederick and Allegany counties, like you've never heard before. The [bug] populations are just through the ceiling."

The change in season, as days shorten and nighttime temperatures start to dip, is nature's call to the brown marmorated stink bug - pest extraordinaire -- to leave its summer gorging grounds and seek refuge inside. What's happening now is a massive population shift from orchards, cornfields and gardens to suburban homes, office buildings and hotels -- the urban U.S. equivalents of rocky outcroppings in the stink bug's native Asia.

Stink bugs are harmless to people and their possessions. They don't bite. They don't sting. They're not known to transmit disease. But their population has grown so tremendously that they are not only causing vexation to homeowners but also, for the first time, wreaking damage to peaches and apples, soybeans and corn, and even ornamental shrubs and trees.

There is no easy way to kill lots of the bugs at once. They have no natural predators in the United States. Pesticides don't work effectively. The insects travel easily -- hitching rides on buses and construction material -- and adapt to winter in homes. As a result, they have flourished, spreading to 29 states since they arrived in Allentown, Pa., in 2001, likely stowaways in a shipping container from Asia. They are native to Japan, Korea and China, where they are known as "stinky big sisters."

And now they are causing a stink in the mid-Atlantic region.

Experts say homeowners should prevent them from coming indoors by sealing cracks and openings around doors and windows. Once the bugs are inside, residents can vacuum them up, remove the bag and put it in the garbage outside. (Beware: The smell may linger in the vacuum cleaner.) Experts warn against using outdoor pesticides.

It's true: 'They smell'

"I'm looking out my window here, and I bet I have 30 of them on the screen," said longtime Middleburg resident Margo Tate. "My husband smushes them and throws them in the trash. They're a mess. They smell when you squish them."

Lori Rice, 48, runs an organic farm in Middletown, in Frederick County. She finds them indoors and outside. Indoor bugs she traps in "death jars" -- pint jars containing soapy water. The soap, she said, dissolves the exoskeleton. Twice a day, she flushes the bugs down the toilet.

On Rice's farm, Asian pears, raspberries and tomatoes have all suffered.

"If all our vegetables hadn't already [been] withered by the heat and drought this year, the bugs would likely have broken our hearts there as well," she wrote in an e-mail.

She is experimenting with spraying soapy water outside.

For people, stink bugs are nowhere near the menace of bedbugs, which feed on human blood. Their resurgence prompted the U.S. Centers for Disease Control and Prevention to issue an unusual statement last month about their public health impact. Stink bugs, by contrast, are a mere nuisance for people, though they are causing farmers real distress.

Maryland's Agriculture Department last week warned that the bug is emerging as a devastating pest to orchard owners and potentially to soybean growers.

"In Maryland this year we have had the most extensive brown marmorated stink bug damage to both tree fruit and vegetables ever reported in the U.S.," said Jerry Brust, a University of Maryland pest expert.

Bob Black, whose 100-acre Catoctin Mountain Orchard in Thurmont, Md., includes peaches and apples, said he has lost about 20 percent of his crop. The bugs suck out juices, leaving pockmarks that make fruit and vegetables unmarketable.

Dairy farmers are worried that cows that feed on chopped-up field corn full of dead stink bugs might develop a bad smell in their milk.

Federal intervention?

Rep. Roscoe Bartlett, a Republican who represents Maryland's rural 6th District, sent a letter Friday, signed by 15 members of Congress, asking U.S. Agriculture Secretary Tom Vilsack and Environmental Protection Agency Administrator Lisa P. Jackson to take immediate action to limit damage caused by Halyomorpha halys.

Because so little is known about the insect, researchers at the U.S. Department of Agriculture and state universities in Maryland, Pennsylvania, Delaware, Virginia and New Hampshire (the bug popped up there for the first time this year) have formed the Brown Marmorated Stink Bug Working Group. Among the priorities: study the bug's basic behavior and biology, identify natural ways to control it and develop public awareness.

Tracy Leskey, a USDA scientist and a leader of the group, made the first positive identification of a specimen in Maryland in 2003, at a gas station in Hagerstown. She tracks them from her research station in Kearneysville, W.Va. Outside Shepherdstown, where she lives, residents have reported having thousands massing on the sides of their homes.

"I have never seen anything like this in my career," said Leskey, 42.

Researchers are racing against the clock to find ways to kill the stink bugs.

At a USDA lab in Newark, Del., scientists have quarantined tiny parasitic wasps -- collected from China and Korea, where they are the bugs' natural predators -- to determine whether the wasps can be used against the stink bugs without harming other species here. The wasps attack the eggs of the stink bugs. That research is likely to take two more years.

The Brown Marmorated Stink Bug

University of Florida
Originally Published on April 2005; Latest Revision in July 2010

The brown marmorated stink bug (BMSB), Halyomorpha halys Stål, is a pest that was first officially reported from the western hemisphere in Allentown, Pennsylvania in 2001 ...

BMSB is polyphagous, and is a pest of several important crops in its native range. In Japan it attacks shade and fruit trees, vegetables, and leguminous crops (Hoebeke 2002). In southern China, it feeds on flowers, stems and pods of various legumes, and also on apple, cherry, Citrus, fig, apricot, mulberry, peach, pear, and soybean as well as other plants.

Unfortunately, it is difficult to assess the damage caused by one species of stink bug, since several species cause similar damage. A similar situation may occur in the southern U.S., as the BMSB spreads south and overlaps with the distribution of the southern green stink bug.

Originally, populations in Pennsylvania were limited to ornamental plants, garden crops, fruit and shade trees in suburban areas and urban landscapes. Damage was observed on several ornamentals, including butterfly-bush (Buddleia spp), and the princess tree (P. tomentosa). Both adults and nymphs fed on the leaves of these two host plants, and leaf damage was very apparent by the end of the season. These two ornamentals may attract the stink bug as it spreads to new areas, and homeowners are likely to be the first to see this new pest. Significant damage was also reported on urban peach and pear crops. Following the first official identification of BMSB, Bernon et al. (2004) found BMSB on over 60 host plants.

As the BMSB continues to expand its range, it is likely to invade agricultural areas and may pose a risk to various crops. Nielson and Hamilton (2009) conducted an extensive study of BMSB populations at farms in New Jersey and Pennsylvania, and found approximately 25% damage per fruit tree. These studies critically indicate the potentially increasing pest pressure that may occur in tree fruits, particularly pears, apples, and peaches, as a result of the introduction of BMSB. Nielsen and Hamilton (2009) predict that pest pressure from BMSB could be more severe in southern U.S. peach-producing states, as it is possible that two generations per year would occur in warmer climates.

Stink Bugs Invading Dan River Region Homes

GoDanRiver.com (North Carolina)
September 25, 2010

Many residents can’t leave their homes without bumping into stink bugs crawling on screen doors and around entryways trying to sneak in.

An unprecedented population of the brown marmorated stinkbug — an invasive species — has local homeowners calling exterminators for help.

“We’re definitely getting a lot of calls about stink bugs, that’s for sure,” said John Adkins, owner of Four Seasons Pest Control on Franklin Turnpike.

Calls started picking up within the past two weeks. Adkins estimates about 50 calls so far, but it’s still early in the season.

“This year for some reason, they’ve gotten a lot worse,” Adkins said. “I’m seeing them all around.”

Eric Day, entomologist and director of the insect identification lab at Virginia Tech’s Department of Entomology, agreed the numbers surged this year.

While Virginia hosts native stink bugs, the ones on the screen doors and entering homes are a new species to the state, Day said.

The brown marmorated stink bug — a native agricultural pest for China and Japan — first arrived by accident to eastern Pennsylvania in 1998. The bugs showed up in the Roanoke area in 2005 and are spreading across the state, he said.

The dry, hot summer helped increase numbers for both native and brown marmorated stink bugs, but the invasive species’ numbers surged because they have no natural enemies to keep the population in check, Day explained.

“So, it’s kind of run amuck,” he said.

Yet, the bugs are harmless. They aren’t poisonous and don’t cause structural damage to homes. They just want a place to live for the winter.

Of course, when squashed or threatened, they excrete an icky smell.

“They are a classic nuisance pest,” Day said.

Vegetable gardens and farms had been dealing with the immature stink bugs or “nymphs” all summer, he said. They like to feed on seeds and fruit, like grapes, apples and peaches. In some areas, they fed on soybean pods.

What can homeowners do?

Companies like Four Seasons can treat in areas where the bugs are trying to get in, but the best thing homeowners can do is winterize their homes — sealing up cracks and crevices around door seals and windows, Adkins said. That’ll help keep stink bugs and other insects out while making your home more energy efficient.

“It makes us a little bit more aware of our homes and how easy it is for insects to invade,” Adkins added.

Dodson Pest Control on Memorial Drive is definitely getting more calls this year than last year, said District Manager Randy Mullens.

This year, the company is offering perimeter treatments in areas where the stink bugs are most likely to land, he said. Stink bug numbers are so great, customers are asking for treatments.

He expects stink bug traffic will pick up as the weather cools and Dodson Pest Control will deal with them through November.

Mullens lives in Franklin County, where stink bugs adorn his home.

“We’re starting to see a lot more,” Mullens said. “I’ve never seen anything like it.”

Move Over, Bedbugs: Stink Bugs Have Landed

The New York Times
September 26, 2010

When they retreated from the Battle of Gettysburg, Confederate troops passed by the area that is now Richard Masser’s orchards. If only the latest enemy — the brown marmorated stink bug — would follow suit.

A stinkbug.

Damage to fruit and vegetable crops from stink bugs in Middle Atlantic states has reached critical levels, according to a government report. That is in addition to the headaches the bugs are giving homeowners who cannot keep them out of their living rooms — especially the people who unwittingly step on them. When stink bugs are crushed or become irritated, they emit a pungent odor that is sometimes described as skunklike.

Suddenly, the bedbug has competition for pest of the year.

Farmers in Maryland, New Jersey, Pennsylvania and other states are battling a pest whose appetite has left dry boreholes in everything from apples and grapes to tomatoes and soybeans. Stink bugs have made their mark on 20 percent of the apple crop at Mr. Masser’s Scenic View Orchards here. Other farmers report far worse damage.

“They’re taking money out of your pocket, just like a thief,” said Mr. Masser, flicking stink bugs off his shirt and baseball cap as he overlooked his 325 acres, a few miles south of the Pennsylvania border. “We need to stop them.”

No one seems to know how. Government and university researchers say they need more time to study the bug, which has been in the United States since about 1998. Native to Asia, it was first found in Allentown, Pa., and has no natural enemies here.

Some people noticed an increase in the stink bug population last year, but all agreed that this year’s swarm was out of control. Researchers say the bugs reproduced at a faster rate this year, but they are unsure why.

“These are the hot spots right now, but they’re spreading everywhere,” Mr. Masser said. “They even found them out in Oregon.”

Populations of the brown marmorated stink bug — different from the green stink bugs that are kept in check by natural predators here — have been found in 15 states, and specimens in 14 other states, according to the United States Department of Agriculture.

The bug travels well, especially as it seeks warm homes before the onset of cold weather.

“It’s an incredible hitchhiker,” said Tracy Leskey, an entomologist with the Agriculture Department’s Appalachian Fruit Research Station in Kearneysville, W.Va. “The adults are moving and looking for places to spend the winter.”

The research station is among three laboratories looking for a solution. Government and university researchers also formed a working group this summer. But Kevin Hackett, national program leader for invasive insects for the Agriculture Department’s research arm, said no immediate solution was in sight.

“We need to do considerable more research to solve the problem,” he said. “We don’t even have a way to monitor the pests. I’m confident that we have excellent researchers. I’m not confident we’re going to find a solution immediately.”

The department is spending $800,000 this fiscal year on stink bug research, double last year’s budget, Mr. Hackett said. But he estimated that seven more full-time researchers were needed, at a cost of about $3.5 million a year for salaries and research expenses.

In Asia, a parasitic wasp helps control stink bug populations by attacking their eggs. Unleashing those wasps here, however, is at least several years away because they would first need to be quarantined and studied.

There has been limited success using black pyramid traps in orchards, Ms. Leskey said. The traps contain scents that trigger sexual arousal. The nymphs, or young bugs, respond seasonlong, Ms. Leskey wrote in a recent report, but adults respond only late in the season, in late August.

Representative Roscoe G. Bartlett, Republican of Maryland, convened a meeting last week of officials from the Agriculture Department and the Environmental Protection Agency. He is pushing to have the stink bug reclassified, which would allow farmers to use stronger pesticides, and is advocating that the Agriculture Department reallocate $3 million of its budget for research.

A problem that can arise when more pesticides are used, experts and farmers say, is that many years’ worth of effective “integrated pest management” can be ruined in the process. Farmers kill some pests but allow others to live because they prey on yet other pests. Wasps, for example, eat worms that otherwise would kill crops.

“It is a way to use nature’s own defenses against pests in orchards,” said Steve Jacobs, an urban entomologist at Pennsylvania State University. “That’s been finely tuned and works well. This brown marmorated stink bug blows all that out the window. You kill them today, new ones come tomorrow. So this is a serious problem.”

Meanwhile, homeowners in the region are coping with this latest nuisance.

Vicky Angell of Thurmont, Md., said she first noticed the stink bugs last year, but “not in flocks” like this summer. She kills about six a day and suspects that they get inside her home when she leaves the door open to let the dog out.

Damage to crops from stink bugs in mid-Atlantic states has reached critical levels, a government report said.

Ms. Angell said she flushes them down the toilet after catching them in a napkin. Other people use their vacuum. And many have turned to exterminators.

Stink bugs, whose backs resemble knights’ shields, do not bite humans and pose no known health hazards — even the fruit they have gotten to is edible, once the hardened parts are cut out. They leave small craters on the surface of an apple or pear, and the inside can get brown and corklike. Females can grow to nearly the size of a quarter. “Marmorated” refers to their marbled or streaked appearance.

Still, sometimes they are just too close for comfort. Ms. Angell said she got a surprise when she put on her pants Friday morning, having washed them and left them to dry in her laundry room.

She felt something in the right rear pocket.

“I thought I left a piece of paper in them when I washed them,” she said.

But it was not paper.

“Pulled it out. He was alive. Stink bug. Flushed him down the toilet,” she said. “I thought, I’m glad I didn’t sit on that.”

Kelli Wilson of Burkittsville, Md., said her home had been overrun by the bugs, especially in the past week.

In the afternoon sun, the north-facing exterior of the house “is black with stink bugs,” she said. “It looks like the wall is crawling.”

Mrs. Wilson’s husband, Raymond, skipped services on Sunday at St. Paul Lutheran Church in Burkittsville to remove stink bugs from the house. Mrs. Wilson discovered a little hitchhiker as she and her children arrived at the church.

“I just pulled into the parking lot and there’s one on my purse,” she said. “They travel with me now.”

Mr. Jacobs, the urban entomologist, said the response to stink bugs so far is not an overreaction.

“I’m standing here in my living room watching some of them crawl up my walls,” he said. “The best thing to do is make your house as tight as possible. Use masking tape to seal around sliding glass doors, air-conditioners.”

Mr. Masser, the Sabillasville farmer, said that he had not yet raised his prices to offset losses, but added that it was a possibility next year if a solution to the stink bug invasion was not found.

“Stink bugs are going to destroy a lot of food — it’s just starting,” he said. “When Joe Blow starts hollering because he can’t find the food he wants, they’ll respond then.”

The Plague of the Halymorpha Halys in Our Nation's Capitol

And when he had opened the fourth seal, I heard the voice of the fourth beast say, Come and see.
And I looked, and behold a pale horse: and his name that sat on him was Death, and Hell followed with him.
And power was given unto them over the fourth part of the earth,
To kill with sword, and with hunger, and with death, and with the beasts of the earth.
--Revelation 6:7-8

And the LORD said unto Moses, Stretch out thine hand over the land of Egypt for the locusts,
That they may come up upon the land of Egypt, and eat every herb of the land, even all that the hail hath left.
And Moses stretched forth his rod over the land of Egypt,
And the LORD brought an east wind upon the land all that day, and all that night;
And when it was morning, the east wind brought the locusts.
And the locusts went up over all the land of Egypt, and rested in all the coasts of Egypt:
Very grievous were they; before them there were no such locusts as they, neither after them shall be such.
For they covered the face of the whole earth, so that the land was darkened;
And they did eat every herb of the land, and all the fruit of the trees which the hail had left:
And there remained not any green thing in the trees, or in the herbs of the field, through all the land of Egypt.
--Exodus 13:10-15

Word of Life Ministry
September 24, 2010

When the LORD God was trying to convince the Pharaoh of Egypt to free the Israelites, plagues came upon Egypt. One of the plagues described in Exodus10:14, 15:

"And the locusts went up over all the land of Egypt, and rested in all the coasts of Egypt: very grievous were they; before them there were no such locusts as they, neither after them shall be such. For they covered the face of the whole earth, so that the land was darkened; and they did eat every herb of the land, and all the fruit of the trees which the hail had left: and there remained not any green thing in the trees, or in the herbs of the field, through all the land of Egypt."

This was the eighth plague sent upon Egypt because the Pharaoh was a stubborn man with a hardened heart. And more plagues were sent upon he and his people before he gave in to the will of the LORD.

The LORD gives plenty of warnings to those whom he wishes to persuade. And like Egypt of old, America should examine itself as a nation and as a people and try to discern what the LORD is after. America has had costly natural disasters. America has had political disruption, such as a nearly decade long war against terrorist forces. America has had tremendous financial disaster brought on by its elected leadership. And all the while, the leadership continues to say there is more than one way to heaven.

Now a plague of a different sort is annoying all who live within 200 miles of Washington, D.C. It is causing damages from 20- to 100% on farms across Maryland, Pennsylvania and up the New England coastline. It is invading houses by the millions.

Maryland Republican Congressman Roscoe Bartlett recently organized a briefing on the threat, bringing together congressional staff, regional and federal agricultural officials and others to understand the problem and to try to find ways to combat it. Bartlett was quoted in the Baltimore Sun saying,

"If you wanted to design a terrorist bug, it would have the features of the brown marmorated stink bug."

Yes, the plague is called the stink bug. It is a bug thought to have made its way to the United States in containers shipped from China. And if one smashes the bug, it will take no time to know why it is called the stink bug. It has no natural predators and its population is exploding.

The irony is that this bug is invading the area surrounding the nation's Capitol--the NBC affiliate in Washington, DC led with the story "Stink Bugs taking area by storm." Indeed, we have been gathering up hundreds of stink bugs each morning in our windows and on our walls. Perhaps the stink bug from China is a not so subtle message about the leadership in America and Americans' tolerance of it.

And the seven angels which had the seven trumpets prepared themselves to sound.
The first angel sounded,
And there followed hail and fire mingled with blood,
And they were cast upon the earth:
And the third part of trees was burnt up,
And all green grass was burnt up.
And the second angel sounded,
And as it were a great mountain burning with fire was cast into the sea:
And the third part of the sea became blood;
And the third part of the creatures which were in the sea, and had life, died;
And the third part of the ships were destroyed.
And the third angel sounded,
And there fell a great star from heaven, burning as it were a lamp,
And it fell upon the third part of the rivers,
And upon the fountains of waters;
And the name of the star is called Wormwood:
And the third part of the waters became wormwood;
And many men died of the waters, because they were made bitter.
(Revelation 8:6-11)

Other Invasive Species from China Have Been Introduced in the U.S.

Asian Carp
Asian Carp are a significant threat to the Great Lakes because they are large, extremely prolific, and consume vast amounts of food. Many in the Great Lakes region fear that the fish, because they are voracious filter feeders and prolific breeders, could wreck havoc on the region’s fisheries by disrupting the food chain, as it has done in parts of the Mississippi, Missouri and Illinois Rivers. The Asian carp grows rapidly and can weigh up to 30 pounds within a few years, and females are highly fecund, able to produce as many as a million eggs at a time. The fish reproduce so swiftly that the species now constitutes up to 90 percent of the biomass in some stretches of the Mississippi and Illinois Rivers. The Asian carp is also a spectacular leaper, able to fling its body 10 feet above the water or higher, a phenomenon caused by noise, particularly from motorboats. As a result, in rivers where the carp has taken over, pleasure boaters, water skiers and fishermen are increasingly being forced to dodge huge flying fish as they motor down their favorite waterway — not the most pleasant way to spend an afternoon.



Asian Snakehead Fish
During the summer of 2002, an exotic fish species called the Northern Snakehead was found in a pond in Crofton, Maryland, about 20 miles north east of Washington, D.C. It is a voracious top-level predator, meaning that it has no natural enemies, and could decimate populations of native fish. About 90% of its diet consists of other fish, though it also eats crustaceans, insects, and plants. Snakeheads can breathe air and survive for up to four days out of water, and can survive for longer periods of time when burrowed in the mud. They are capable of traveling over land to new bodies of water by wriggling their bodies over the ground. Little is known about the toothy fish other than it is considered a top-level predator from its native region of China. Sportsman are advised to kill the fish and not simply “bank” it since the species is capable of living out of water for several days and crawling using its fins to propel it.



Lionfish
Lionfish native to the South Pacific, Indian Ocean and Red Sea have invaded Florida. They live among their world-famous coral reefs. With few natural predators, they have been rapidly expanding in Caribbean and Atlantic waters, voraciously preying on local fish, shrimp and crab populations across the region and in Florida. Some scientists are now listing the invasive lionfish species among the top 15 threats to global biodiversity. They are a danger to native marine life through predation. U.S. government researchers believe the red lionfish was introduced into Florida waters during Hurricane Andrew in 1992 when an aquarium broke and at least six fish spilled into Miami's Biscayne Bay.

Burmese Python
Over the years many big animal warehouses in Florida have been hit hard by hurricanes, and the Burmese python population they had in captivity escaped. Also, starting as pets, the Burmese pythons have been released into the wild by their owners who did not know what to do with them after they got too big to handle. This southeast Asian predator is taking over the Florida Everglades by competing with the native animals for space and food. Since they have no natural predators their population has been exponentially increasing. And a new species of invasive snake, the African rock python, has recently been found on the loose as well. At least five rock pythons, one that measured 14 feet long, have just been captured in Miami-Dade county. Now experts' fears are mounting that the Burmese and African rock pythons will begin breeding — and give rise to a new, dangerous 'super snake.'



Editor's Note: Some claim the following methods will kill stink bugs:

• Mix Borax and water with a little Dawn dishwashing liquid in a spray bottle.


• Mix salt and Dawn with water.


• Mix one part Dawn to three parts water.


• Spray them with rubbing alcohol.

Invasive Species from South America

USA TODAY
February 25, 2011

Global Fire Ant

Red fire ants stand a good chance of colonizing half the world's land masses in the coming years and it's all our fault. The stinging ants originally come from South America, but genetic analysis of populations that have invaded much of Asia already show they all started in one place - the southern United States.

The Solenopsis invicta invasion began when the ants, originally from South America, appeared in the American south. It's believed they first arrived in the 1930s through the port of Mobile, Ala., on cargo ships, possibly in dirt used as ballast.

In the south the stinging, biting, highly aggressive ants became an established and expensive pest. Humans there have learned to walk carefully, as stepping on a red ant hill can result in thousands of the tiny stinging ants swarming over feet and legs.

Over the past 20 years, as the global movement of goods, foods and people began to explode, the ants went on to march. Newly invaded areas included California, China, Taiwan, Australia and New Zealand.

They aren't just an annoyance. In the United States alone costs connected to control, medical treatment and damage to property for the invaders are estimated to be greater than $6 billion annually.

Now researchers in the United Stations and internationally have shown that the invasions came not from the ant's native South America, but from their colonies in the American South. Each major invasive wave is associated with an independent U.S. ant population. The only exception are the colonies in Taiwan, which appear to be most closely genetically related to the ones in California, which originally came from the American south.

The research is published in this week's edition of the journal Science.

This 'jumping off' type of expansion is called the invasive bridgehead effect and is a common way for invasive species to extend their range.

"Given that most invasions are shaped by trends in human transport, their frequency of occurrence will probably increase with increasing global trade and travel," the researchers write.

Knowledge of how the ants spread can help scientists look for the most effective biological control agents available to combat the ants, says DeWayne Shoemaker, a U.S. Department of Agriculture scientist affiliated with the University of Florida's Institute of Food and Agricultural Sciences and senior author on the paper.

One tactic that's show success is the release of phorid flies, which inject their eggs into ants. When the egg hatches, the maggot develops in the ant's head, eventually decapitating it. The maggot turns into a fly and the cycle repeats.