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Black fire ants July 11th, 2021 by

The surest way to tell if you have black fire ants in your garden is to accidentally stand on or near their nest. The ants will crawl through your clothes first and then start stinging you all at once. You may have to go inside and take off your trousers to find all of the ants in your pants. A second diagnostic test of black fire ants is to plant a vegetable seedbed, and wait for it to come up, but it never does. The ants have eaten all your seeds.

These ants love seeds and they will dig up every one you plant in their foraging area.

You can try dousing their nest with boiling water, insecticide or gasoline (and then lighting it). I’m just kidding, but it may not even work; these ants are pretty tough. Or you can take Rachel Carson’s suggestion, and fight pests with biology, not chemistry.

Years ago, while working with my student Eloy González on his entomology thesis at El Zamorano, Honduras, by total serendipity we learned that fire ants can be perfectly controlled with raw grains of rice.

Here’s how it works. Plant your vegetable seedbed any way you like. Then sprinkle a handful of raw rice over the surface. The black fire ants are omnivorous, but they prefer dense food packages like seeds or other insects. The ants also know a bargain when they see one. The ants will haul off your rice grains and ignore your smaller, harder-to reach soil-covered vegetable seeds.

Once your vegetables come up, the black fire ants will lose interest in them. However, the ants will continue to patrol your vegetable patch, looking for insect pests to drag back to their nest, to eat.

If you don’t want to use rice, try bread crumbs, bits of stale tortillas or other food scraps.

In our garden, we have had no insect pests, except for the Mediterranean fruit flies. Our patchwork of many species of trees and vegetables confuses most insect pests. And because we have never applied insecticides, we have many beneficial insects that kill most of the herbivorous ones before they can become pests. We manage our black fire ants with the rice trick, and by not standing on their nests. They repay us by helping to keep our vegetables pest-free.

If you live outside of tropical Central or South America, you may never have to deal with black fire ants. But wherever you live, you can always look for ways to live with insects, with biology, not chemistry.

Further reading

Paul has his own story about Vietnamese farmers who educate weaver ants, to protect their orchards from insect pests.

Ants as friends.

Related Agro-Insight blog stories

Ants in the kitchen

Sugar sweet ants

The smell of ants

When ants and microbes join hands

Videos about insects that hunt and control insect pests, from Access Agriculture

The wasp that protects our crops

Promoting weaver ants in your orchard

Weaver ants against fruit flies

Scientific names

The black fire ant, also called the tropical fire ant, is Solenopsis genimata. The red fire ant, the so-called “imported” one is Solenopsis invicta. The red fire ant is native to Argentina, and slipped into the USA, possibly as a stowaway on a ship, after 1933. in Silent Spring, Rachel Carson tells the story of how the US Department of Agriculture lost its chemical war against the red fire ant. That red ant is still thriving in North America. Unlike the black fire ant, which builds discrete, ground-level nests, the red one builds, a tall, conspicuous entrance to its burrow.

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