Little yellow ants start U.S. colonies in S. Florida
FORT LAUDERDALE — Florida provides a home to ghost ants, crazy ants, red imported fire ants and more than 50 other non-native ant species, an abundance of transplants from South America, Africa and Asia that crawl, scurry, sting and bite. Now, a new species has joined their ranks.
Say hello to the little yellow ant, a potentially damaging species from Madagascar that has set up colonies in the Riverland section of southwestern Fort Lauderdale, its first known foothold in the continental United States.
Little yellow ants don’t bite, but everything else about them is bad news. These tiny ants proliferate by the millions in super colonies served by thousands of egg-bearing queens. They could threaten South Florida’s agriculture, including citrus. Difficult to eradicate once they establish a colony, they’re uninvited dinner guests in the neighborhoods they infest, swarming kitchen counters and anyplace else that might have something to eat.
“When you have a barbecue with friends outside, within minutes whatever food you have waiting to be put on the barbecue is going to be covered in ants,” said Thomas Chouvenc, a biologist at the University of Florida Institute of Food and Agricultural Sciences. “People are not going to like it.” The presence of Plagiolepis alluaudi is South Florida was detected earlier this year by Chouvenc, who specializes in termites. He noticed the yellow ants around his house in Fort Lauderdale and then discovered them throughout the Riverland neighborhood.
“The dynamic of the ant species in my backyard was changing,” he said. “I could see these ants showing up and the big-headed ants were vanishing. Then these little guys started showing up in my bathroom, my kitchen countertop, my dining room, in my baby’s room. They will form this massive foraging trail to bring the food back to their nest, which is somewhere outside. Out of all the ants I’ve had to deal with in Florida, this has been the most annoying so far.”
South Florida’s warm, moist climate has long provided a congenial home for species from around the world, arriving as inadvertent stowaways on boats, through the region’s seaports or via the exotic pet trade.
Iguanas, lionfish, wild hogs, tegu lizards, monk parakeets, vervet monkeys, northern curlytail lizards, Burmese pythons, boa constrictors, bullseye snakeheads and Muscovy ducks all have found homes somewhere in South Florida’s swamps, coastal waters, forests and neighborhoods. They thrive here for the same reason people come to South Florida from New York, Cleveland and Montreal.
“We have a very hospitable climate,” said Andrea Lucky, a biologist at the UF specializing in ants. “It’s warm all year round. Especially in South Florida, we’re not dealing with freezes. These global tropical
and subtropical species that get shipped around the world have a very nice landing pad in Florida because it’s humid, it’s warm, there’s a lot of vegetation and we have a lot of ports of entry.”
The ants often establish their colonies outside, sending foraging parties to raid houses. And these colonies are connected, forming supercolonies. So while standard ant baits can work, Chouvenc said, they have to be set outdoors and they may eliminate only one branch of a colony.
As irritating as the ants may be for residents, they could be worse for farmers. The ants don’t directly attack crops, but they protect the insects that do.
They guard aphids, scale insects and mealy bugs, pests that suck the sweet sap from a variety of plants. In return for protecting these pests from predators, the ants consume the sugary fluid called honeydew, discharged by the insects. So prized are these agricultural pests by the ants, that ants have been known to bring the sap-sucking insects’ larvae to their nests, where they grow to adulthood.
Among the insects with which ants have this relationship is the insect that transmits citrus greening bacteria, a major cause of disease in Florida’s citrus groves.
“These ants seem to be very problematic with the pest insects they might protect,” Lucky said. “I think we have to be concerned about the introduction of ants that can reach really large numbers because they can help foster communities of insects that can be destructive on a much larger scale.”
From their home off the African coast, the ants spread via shipping lanes. An article by James Wetterer, a biology professor at Florida Atlantic University, documents evidence of the little yellow ant throughout the world, including previously unreported locations in the Caribbean and reports from greenhouses in England, Germany and Switzerland.
It’s unclear how yellow ants arrived in Fort Lauderdale, but Chouvenc said they may have come to South Florida on a yacht or other small boat or in a potted plant.
“These guys are fantastic hitchhikers,” he said. “All they need is a potted plant and they sneak in on the root part and establish a nest, and if that plant gets moved from southeast Asia or the Caribbean or Hawaii or wherever it is. I think this is here to stay, unfortunately.”
A key question is the extent of the little yellow ant’s South Florida range. Most neighborhoods don’t happen to have a professional entomologist walking around who would notice a change in the local ant population, so it could well be that the ant has established itself widely throughout the region.
“We want to know how far it is, whether it’s in just a small part of Riverland in Fort Lauderdale,” Chouvenc said. “At this point, I don’t think it is anymore. It’s just a matter of time before we start seeing it all around.”
Whether or not they’re brought under control in particular areas, Chouvenc said they’re likely to stay, becoming a permanent part of Florida’s rich diversity of non-native ant species.
“This is one more on the list,” he said. “Here’s the good news: It doesn’t bite, it doesn’t sting. They’re just very annoying.”