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Northwest Iowa Dairy Outlooks

A local discussion of current science and issues concerning dairying in northwest iowa

Dr. Sonja Swiger with AgriLife Extension notes, if you haven’t tried them yet, fire ant baits are the best tools for really managing fire ants.  They are relatively inexpensive, require little labor to apply, and are safe for both you and the environment.  The biggest drawback of baits is that they cannot be used all year round. Instead applications must be timed to periods when fire ants are actively looking for food, foraging in ant worker lingo.

Many years ago a researcher at Florida State University, named Sanford Porter, spent an entire year of his life (three times a day, once a week) monitoring fire ants coming to little bits of hot dog. Along the way he carefully monitored surface and below-ground soil temperatures, relative humidity, time of day, soil moisture, rainfall, and air temperature.  Porter found that the best way to tell when fire ants would be out foraging (and thus, when they are most likely to find and collect bait) was when the temperature of the soil at about an inch was between 70 and 95 degrees F.  While fire ants will forage outside that range, these are their favorite temperatures.

This morning and afternoon I went outdoors and took the soil temperature in the lawn surrounding my office in Dallas, TX.  The temperatures at one inch averaged between 74 and 82 degrees, in morning and afternoon. This is the sweet spot for fire ants, and lets me know that fire ant baiting season is back again!

The best time of year for fire ant bait applications in north Texas is usually between May and September.  While the ideal baiting time will vary from north to south, the soil temperature rule of thumb seems pretty consistent.  You can check your own soil temperature with an inexpensive metal thermometer, like those used for outdoor grilling.

By the way, soil temperature is also changes throughout the day. Today, anytime during the day would be a good time to broadcast a fire ant bait. But as any seasoned Texan will tell you, there’s a mighty big difference in temperatures between May and July.  In July soil temperatures, even at one inch-depth, soar well over 100 degrees, effectively shutting down most fire ant foraging during the day.

During the hot months, the best time to apply fire ant bait is late in the evening. Bait applied in the morning hours, even when soil temperatures are still favorable, are exposed to high temperatures and bright sunlight, both of which are likely to render bait less tasty to ants.  By applying baits late in the day, they will be available to fire ants during their most favored time for foraging, throughout the night.

To learn more about the benefits of baiting for fire ants, and how to select the right bait product, see the Texas Two Step Method brochure.  And serve those fire ants some tasty baits.

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