With all the types of ants in the world, over two hundred and fifty varieties call Florida home. With all these types of ants, we certainly don’t need any more. But, just because they aren’t welcome, doesn’t mean they won’t find their way here. Through commerce, imported vegetation, and natural migration, they continue to find their way into the Sunshine State. In the first two articles of this series, we discussed common pest ants in Florida. Now we are going to look at some of the top invasive species here in our beautiful state.
Invasive species can wreak havoc on the environment, damage agriculture, injure humans and animals, and push out native species beneficial to the region. These types of ants are a significant problem in Florida.
- Argentine Ants
- Tawny Crazy Ants
- Yellow Ants
- Trap-Jaw Ants
Linepithema humile or the Argentine Ant, is an invasive species from South America. They first appeared in the United States around 1880 via coffee ships from Argentina ported in New Orleans. They are rapid expanders and outside of their homeland have grown to be entirely communal toward each other, forming what is known as unicoloniality. Ants from one nest will breed, move to a new nest, but not show aggression toward other ants of the same species that move into their territory. They will, however, dismantle populations of native ants that are beneficial to the area. For example, the Florida Harvester Ant, which is responsible, in part, for the planting of seeds and the churning of soil, allowing for better absorption after rainfall.
They are not very large ants, but they cause considerable problems for the environment where they take up residence. Workers measure at about 2.5-3mm (about 1/8″), while queens measure much larger at 4-6mm (about 1/4″) in length. They vary in color from light to dark brown and have a triangular-shaped head. Argentine Ants forage for sweets, including young plants, fruit, and the honeydew of crop devastating insects like mealybugs, aphids, and scale insects. Because they are sweet feeders, they can also disrupt bee populations by foraging nectar before the native pollinators have the chance to feed. This practice disrupts natural pollination methods and endangers the plants’ ability to fertilize.
Because this species of ant is a rapid expander and displays no aggression toward neighboring nests of the same species, they can effectively grow super colonies rapidly. Queens can lay up to sixty eggs per day and is estimated that for every one thousand worker ants, about 15 queens exist in a colony. They are a highly adaptive species and prefer to nest in areas that are moist, including under stones and lumber, in fallen tree limbs, along sidewalks, and beneath plants. Indoors they typically nest near water pipes, under sinks, and in potted plants. Colony structures have proven to be challenging to manage because of this rapid expansion. Sweet baits work best to reduce populations, but finding the entirety of a colony is necessary to prevent future infestations. The response of Argentine Ants to spray insecticides is to promptly move to a new location, queens and workers alike will quickly pack up and move to a new location at the first sign of disturbance. Protocols for exterminations can take weeks or months to destroy a supercolony of Argentine Ants entirely.
Tawny Crazy Ants (TCA)
Nylanderia fulva or Tawny Crazy Ants are another accidental import from South America. There are good news and bad news associated with these pesky ants. They are a natural enemy of fire ants. But certain species of fire ants, like the Little Fire Ant, are native to Florida. They help to control the population of boll weevils, caterpillars, and other pests that can destroy crops such as cotton or sugarcane, which is Florida’s number one field crop. Even Red Imported Fire Ants can be beneficial, keeping down the number of rodents, ticks, fleas, and small reptiles. Swapping out Tawny Crazy Ants for these beneficial fire ant species could have an ecologically devastating impact on both agriculture and local wildlife. For humans, the Tawny Crazy Ant has caused short circuits to electrical components such as air conditioning units and computers after nesting inside.
Identification & Nesting Habits
The Tawny Crazy Ant, previously known as the Caribbean Crazy Ant, is a small ant, with workers measuring around 2mm (less than 1/8″) and queens at 4mm (around 1/4″). They are golden to reddish-brown. They can easily be spotted because of their erratic movement. Nests, however, are challenging to locate as TCA are similar transient ants like the Argentine Ant with the ability to relocate on a moment’s notice. As they disrupt native insects drying up populations of beneficial bugs, they will nest as long as there is an available food source. Relocation occurs once that source is no longer viable. Tawny Crazy Ants can also be devastating to bee populations. This species has been observed killing honeybee larvae so that they can use the hive as a nesting area.
Controlling populations of TCA has been proven to be ineffective because of their super colony nesting habits. Currently, home pesticide treatments have not been effective in eradicating colonies of Tawny Crazy Ants. Home management of these pests includes typical ant remediation techniques such as sealing of cracks and gaps in foundations and walls to prevent indoor infestation. Removing yard debris and limiting yard waste and clutter (which provide moist environments) will also help to reduce outbreaks by restricting habitat. Professional Pest Control services are recommended to completely eradicate populations, especially since they often occur over property lines.
Reports from the University of Florida, Institute of Food and Agricultural Sciences confirm the detection of the species Plagiolepis alluaudi, or the yellow ant in the United States as recently as 2017, near Ft. Lauderdale. This observation is the first time this ant species have been spotted in the continental US. However, earlier reports have detected the species in Hawaii. There is little known yet about the impact this invasive species will have on the Florida ecosystem as researchers are still studying it. What is known thus far is that colonies of yellow ants are displacing all other ant species, such as the BigHeaded Ant and Argentine Ant. While those are both non-native species to Florida, the fact that such a tiny ant can displace much larger ants is not good news for the environment. Yellow Ants do not bite or sting but are hard to detect because of their tiny stature and dull coloring, which makes them easily blend into the landscape. Yellow ants, however, are aggressive toward other species and competitive for food sources, which is how they are displacing other native and non-native ant species. They are similar to the Argentine and Tawny Crazy Ant in their supercolony nesting system. This system makes management of these types of species difficult as they often surpass property lines. The supercolonies have multiple queens, and since the goal of any ant remediation is to destroy the queen, having multiple nests with numerous queens makes the eradication that much more difficult.
They are a pest which prefers outdoor nesting in plant debris, vegetation and on living trees, but will forage inside through cracks and gaps in foundations and exterior walls. Yellow Ants prefer sweets, and these types of baits have proven to be effective in managing colonies. However, where the population is dense, re-infestations can and often do, occur. Being a sweet feeder also poses an additional concern for agriculture, as these ants associate with crop-damaging aphids, mealybugs, and scale insects.
The ants originated in Madagascar and have been detected mainly in European greenhouses. They have become a massive problem on Christmas Island in Australia, killing large populations of land crabs. The impact on Florida ecosystems will require further investigation.
Trap-Jaw Ants, Odontomachus haematodus, have been reported in the major metropolitan areas of Orlando, Gainesville, and Pensacola as recently as 2014. They have been spreading across the Gulf Coast region and were detected first in Alabama, Mississippi, and Louisiana as early as 1956. Trap-Jaw Ants originate from South America and have most likely spread through commerce. They do have stingers that contain venom, but the scariest thing about them is that they can (and will) open those mandibles at a 180-degree angle, pierce them into the ground and launch themselves at you if they feel threatened. This ant is another species with very little data available about nesting habits, and environmental impact.
Whatever types of ants you encounter, they can be a nuisance. However, invasive ant species can bring their own sets of problems. They create economic burdens on both homeowners and government; they lower the biodiversity of the areas they infest damaging native species of plants and animals alike. They also can be harmful to agriculture by either destroying crop-helping insects or attracting crop-destroying insects.
Humans can help keep ant populations in check by maintaining clean yards, free from debris, and clutter. To prevent home infestations, the common practice of sealing cracks and gaps in foundations and exterior walls is always a good measure. Putting cleanliness as a top priority inside the home will discourage foragers from venturing inside. If you do happen to see ants, you should immediately put into practice the management systems described throughout this series. If it is beyond home remediation solutions, contact pest control management professional.
University of Florida Institute of Food and Agricultural Sciences, Entomology & Nematology Department: http://entnemdept.ufl.edu/
University of Texas Urban and Structural Entomology: https://urbanentomology.tamu.edu/urban-pests/ants/
Ant Web (California Academy of Sciences): https://www.antweb.org/
BBC Earth-Battle of the Ants: http://www.bbc.com/earth/bespoke/story/20140908-battle-of-the-ants/index.html
Pests in and around the Southern Home, P.G. Koehler, R.J. Vazquez, R.M. Pereira