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Know Your Fire Ant Baits from Your Granules
and Drenches!
Scott Russell, Extension Agent - IPM.(Fire Ant Project) for Dallas and Tarrant Counties, the Texas AgriLife Extension Service
In the control of red imported fire ant infestations, there are primarily two types of weapons: bait formulated insecticides and contact insecticides. There are big differences between these two groups of products. These products work differently and it is important to understand these differences in order to get the most benefit for the dollar spent.
Bait Formulated Insecticides: A bait insecticide combines an ant-attractive food source with an insecticide. These products are only effective for controlling fire ants when these insects feed on the bait and ingest the insecticide. Because ingestion of these products is required for them to work, they are more specific for targeting fire ants.
There are two general ways in which bait products work: 1) direct toxicants and 2) insect growth regulators or IGRs. Toxicants poison the all stages of ants, including adults, while insect growth regulators only cause the queen to lay infertile eggs and prevent ant larvae from developing into worker ants. Insect growth regulators are slower acting than toxicants, with both types of bait products being slower to kill ant colonies than contact insecticides. One must be patient for these weapons to work from within the colony. While they are slower-acting these weapons are used at much lower rates of insecticide active ingredients and therefore introduce less chemical into the environment. Also, because of the slower rate of action, re-invasion by fire ants is considerably slower than with contact insecticides.
Bait formulated products can be applied to individual fire ant mounds, but they are best broadcast applied over the entire yard at a very low rate. Broadcasting the bait allows ants from all colonies in the treated area to collect the bait, thus no need to locate the ant mounds. Always read and follow all label instructions to assure proper application and deriving for the most benefit from your control effort. Generally, bait insecticides not collected by the ants are rapidly degraded in the environment.
Granular and liquid contact Insecticides: This may be the more common of the two types of products used. These weapons are formulated to kill insects upon direct contact. Contact insecticides, by their nature, are generalist weapons. That is, they kill or affect almost all insects which come into contact with the product or treated area. These products come in many different forms, including granules, dusts, powders and liquids. Some common contact insecticides used for fire ant control are: Dursban®, diazinon, Sevin®, and Orthene®.
In granular formulations, which often contain diazonon or Dursban®, the corn grit or clay particle is coated with the insecticide serves only as a “carrier” and does not attract ants as does a bait. For these products to work, water must be poured over the granules after placing them on the mound so the insecticide is washed into the nest to contact the ants. Otherwise, the product just causes the ant colony to move to a new nesting site - like your neighbor’s yard!
Most contact insecticides must be watered in to wash the active ingredient into the fire ant’s contact zone as described on the product label. When the label instructions are not followed, treatment may not kill the fire ant colony or cause the colony to split into more colonies than before treatment. When applying these products, do not disturb the mound, this alarms workers to protect the queen(s). Since only the ants coming in contact with the insecticide are killed, if the queen(s) is moved away from the disturbance, your treatment will be less likely to kill the queen and thus the colony.
Insecticide treatments do not prevent future fire ant infestations. Fire ants can rapidly re-invade the treated area from adjacent non-treated areas. Locating and treating individual fire ant mounds can be difficult and burdensome. When fire ant mound numbers exceed 5 mounds per average sized yard (10,000 square feet), it is much less expensive, less work, fire ant specific to broadcast a fire ant bait product.
For more information contact:
Paul Nester
Extension Agent - IPM
Fire Ant Project
Harris County
Phone: (281) 855-5600
or visit http://fireant.tamu.edu.
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin. Individuals with disabilities requiring auxilary aids, services or accommodations in order to participate in Extension programs are encouraged to call 281.855.5600 to discuss specific needs.