Fire Ants on the Move

It’s Always Something

Every few years there seems to be a perfect storm that can wreak havoc on the garden. There are droughts, floods, early freezes, damaging winds, hail and more. Sometimes these “storms” come in the form of critters. This year we have been visited by squash bugs, Mexican bean beetles, fire ants and a melon-eating box turtle. As the weather has cooled and a rainy spell broke the late Summer dry pattern, the fire ants have returned to center stage.

An Unexpected Problem

I always look forward to the Fall gardening season. The cool temperatures make it very pleasant to be outside all day. Also, the crops are normally easy to grow, either from seed or transplants, with few pest problems. This year was a little different. I started in August, just like normal, by directly sowing collard greens and kale seeds. They sprouted in a few days, and looked great. Then they disappeared.

It took me a few days to become suspicious of fire ants, but I eventually came around. Only a couple of weeks earlier I had removed the previous crop and tilled to prepare for the fall veggies. Removing all of the vegetative cover took away a food source at a time of year when fire ants are very active. As soon as the new seedlings emerged, the fire ants discovered and harvested them. I have noticed a similar problem, though less severe, with carrots, swiss chard and bok choy.

 

The Saga Continues

It seems that fire ants like to establish patterns. After purchasing a few supplemental collard green transplants, and coaxing the kale along fairly well (which is planted in the same bed as the collards), the fire ants seem to still be interested in that part of the garden. When Debbie harvested a fresh batch of greens for dinner this evening, she noticed our redbor kale is the latest victim. Redbor is a beautiful and delicious kale, and cost a premium compared with the price of my ‘Georgia’ collard seeds. The source of the damage was not obvious at first…the plants were wilted but intact. Then, at the base of several stems we saw the fire ants at work.

I had just treated several fire ant mounds in the yard, and luckily had some leftover spinosad-based bait. After treating the bed with the collards and kale, I inspected the rest of the garden and found a brand-new, HUGE mound that was built in the end of a wood-framed bed in a matter of less than five days. I used the rest of the bag of bait.

Why Now?

As the weather changes, so do the habits of fire ants. During hot, dry summer weather, mounds may not be obvious because they tunnel deeper in the ground trying to stay cool. When temperatures cool down in fall, colonies build mounds above ground and often move their location altogether to warmer or better sheltered places (often at the edge of pavement or on the sunny side of a building).

When wet weather puts an end to a dry spell, fire ants will swarm. Watch for the winged ants on the surface of the mound as they prepare to take flight and mate in midair, often several hundered feet above ground. Once mated, they will begin new colonies.

What To Do

Fire ants are a part of life in the South. They will not be eradicated any time soon, so control is the most likely hope. It is unlikely that there is a treatment out there with absolutely no collateral damage to other species, including the boiling water drench. Baits (as opposed to contact granules, sprays or drenches) seem to be the most likely method to kill fire ants with the least damage to other species. Baits are extremely effective because of the way fire ants eat: only larva digest solids, so the foraging workers bring all food back to the colony where larva digest it and provide food back to the rest of the colony including the queen. When the digested food is lethal, it kills the entire colony.

The most consistent control includes two phases of bait treatment. The first phase involves treating all mounds individually. The second phase, several weeks later, is a whole-yard treatment. If done in Spring or early Summer, this should give nearly season long control. As I have witnessed this year, the control will only last if no new ants try to encroach. I would suggest the two step treatment with continued monitoring for new activity.

Lots of people try gardening, but those who stay with it are (or learn to be) patient and determined. All kinds of gardening provide unique challenges. May we all stick with it, and continue to improve the ways we answer them. Happy gardening!