When the Ground Moves.

When the Ground Moves.

It started with a quiet day, and a curious bag of sand brought into the extension office but inside was more than just sand. It was crawling with tawny crazy ants (Nylanderia fulva), one of Florida’s fastest-spreading invasive pests. Known for their erratic movement and massive colonies that can make the ground seem alive, these reddish-brown ants are now a growing concern for gardeners across some Florida counties. Unlike fire ants, tawny crazy ants don’t sting, but they can nip with their chewing mouthparts. Their sheer numbers can overwhelm outdoor spaces, crawling on people and spoiling the enjoyment of patios, gardens, and recreational areas. They nest in moist, protected areas such as leaf litter, potted plants, and under debris, often forming sprawling colonies with multiple queens.

Beyond being a nuisance, these ants pose serious risks. They’ve been known to cause electrical shortages by infiltrating equipment, sometimes leading to costly damage. In some Caribbean islands, they’ve harmed organic crops, and in Colombia, infestations have even led to the death of small animals due to asphyxiation. Larger animals have been attacked around sensitive areas like the eyes and hooves. Tawny crazy ants also disrupt local ecosystems. Their aggressive spread displaces native ant species and reduces biodiversity. While Florida hasn’t reported agricultural damage yet, the potential remains, especially in organic farming systems.

Identification Tips

Workers are small (less than 1/8 inch), monomorphic, and covered in fine hairs that give them a matte appearance. They have one petiole segment and 12 antennal segments, including a long first segment called the scape. Colonies don’t form mounds but may tunnel in sandy soil. Queens are often found among workers, especially in warmer months. If you suspect an infestation, contact your local UF/IFAS Extension office.

Management Challenges

Controlling tawny crazy ants is notoriously difficult. Spraying alone is ineffective, and most insecticides only work for a few days before ants’ return. Integrated Pest Management (IPM) is the recommended approach. IPM combines multiple tactics, starting with accurate identification and monitoring, followed by strategic product application and habitat modification. Professional pest control services that specialize in IPM are often necessary. Timing is critical, and overuse of products is not only ineffective but may violate legal limits. Keep records of infestation locations to anticipate reinvasion, which typically occurs annually. While complete eradication is unlikely in established areas, population suppression is achievable. Interestingly, research suggests that within about a decade, populations may naturally decline, allowing native species to rebound.

Tawny crazy ants are more than just a backyard annoyance they are a complex ecological and household threat. Awareness, early identification, and professional management are key to minimizing their impact. As these ants continue to spread, staying informed and proactive will help protect your property and Florida’s delicate ecosystems.

For more information call or visit your local extension office or follow the link below.

https://edis.ifas.ufl.edu/publication/IN1076