By Bill McCaleb
Program Assistant for Agriculture & Natural Resources
Virginia Cooperative Extension
According to the University of Florida Extension, the most notorious fire ant in their state is the red imported fire ant. It is well known there for its painful, burning stings that result in pustules and intense itching that goes with it. The effects of a fire ant sting can last up to 10 days and even become infected if broken open. Additionally, some people have allergic reactions to fire ant stings, which can be severe.
A close up of the red imported fire ant. Notice the two petiole nodes at the junction of the thorax and abdomen. Do not disturb fire ant mounds. If you find a mound, notify your local Cooperative Extension Office.
This Central American native is considered an invasive species in the United States. They are aggressive, reddish brown to black, normally a reddish head and thorax followed with a black abdomen where the stinger is. These insects’ range in size from one-eighth to one-quarter of an inch long.
The red imported fire ants can build large nests, usually in the form of visible dirt mounds. In sandy soils, the mounds are wider and usually lower than what you find in clay type soils that we have in Southside Virginia. An older mound, undisturbed will grow as the colony expands. In Florida, Georgia, South Carolina, and Alabama it is not uncommon to find low mounds in warm season turfs like zoysia, St. Augustine, and centipede grasses, while larger mounds are found in cool season grasses such as fescues and rye. For farmers, you will find mounds in undisturbed areas of cool season grasses where cattle are. The diet of these insects is omnivore as they will eat grains, partially decaying vegetative matter, as well as a number of insects, both good and bad.
Where do we find their colonies? Near trees and stumps, as well as spaces under pavements, buildings, and indoor areas. Fire ants have even been known to live inside electrical equipment and utility housings which can result in short circuits. When their nests are disturbed, many fire ants will quickly run out and attack any intruder, so beware.
As I said, fire ants are omnivorous feeders. They will eat carbohydrates, like fruits and sugars, and proteins like insects and meat. This ant also feeds on old cooking grease and oil more than other ants which is why fire ant baits are often oil-based. Oil-based baits are dominated by fire ants which results in native, non-pest ant species being outcompeted for this perceived resource. Workers will forage for food more than 100 feet from the nest. They can forage during both the day and the night, generally when air temperatures are between 70° and 90°F. When a large food source is found, the ants recruit other workers to help take the food back to the colony.
Because of the fire ant’s aggressive nature and painful sting, they have been the target of numerous methods of control. Some of these methods are not effective, such as using club soda, grits, soap or wood ashes, shoveling mounds together and spraying foraging workers. Only about 20% of the colony is foraging at any given time. Thus, contact spraying is ineffective and unnecessarily adds pesticides to the environment. There are unfortunately no control methods that will permanently eliminate fire ants from an area. Using a combination of broadcast bait applications and individual mound treatments with baits can help in controlling these pests. Spot-treatments to prevent foraging ants from entering structures can be done, although they do not solve the underlying cause. Excluding ants from structures by ensuring that doors and windows seal tightly and appropriate sealants are used at the point of entry to ants is also helpful.
Additional information can be found at Alabama Extension, Florida Extension and Texas Extension. While we all are practicing ‘social distancing’ and Halifax County buildings are still closed to the public, due to COVID-19, if you have gardening questions, you can best reach an Extension Master Gardener or Extension staff member by sending an email to email@example.com or firstname.lastname@example.org. If you can’t email, you can call and leave a message at the Extension Master Gardener Help Desk at 434-830-3383, giving us your name, telephone number, and nature of the call. The Help Desk phone is checked regularly and someone will get back to you, although it may be from a different telephone number. Keep washing your hands, wearing your mask, and keep your eyes peeled for any unusual mounds or hills that show up on your property.