Ant Management

Features - Pest Control

A 3-Step Holistic Approach

June 12, 2013

Keeping ants out of your plant can be seen as a three-stage process starting on the outside of the facility and working inward. “You have to realize that ants need only a tiny little crack to get in,” said Cisse Spragins, CEO, Rockwell Labs. “So you really need to start on the outside of the facility.”

Ants can come into plants on incoming goods, including non-food items, with some species that build indoor nests being a year-round problem. But, in general, said Syngenta Technical Services Manager Clay Scherer, “from March through May or June, most ant populations are in an expansion mode.”

As temperatures rise and food and water become more accessible outside, ants ramp up their foraging, becoming more visible and colonizing more areas; populations then peak in summer and slow down in fall and winter. Because of that cycle, Scherer said, it is important to get a handle on pest populations in spring and early summer.

Getting a handle on ants is a matter of working in concentric circles, Spragins explained. “Use the 1-2 punch of repellent on the structure and bait outside that.” Then inside, she added, “Pay attention to sanitation so there is no harborage or moisture for them to live on.

“You really need to look at it holistically. There’s no magic bullet, you have to take it step by step.”

A Three-Step Approach

Because ant control requires an integrated pest management approach, protecting your plant and your product from ants will require a partnership with the pest management professional, whether contracted or internal, and your own quality assurance/food safety, maintenance, and sanitation teams. Although the specifics of a program can vary by plant and contracted professional, the following is a general overview of a three-step holistic approach to ant prevention and control.

1. Eliminate Colonies.
The first step in preventing invasion by ants is creating a protective band around the property by eliminating ant colonies that exist there, Spragins said. This is best done with baits, which worker ants will forage and carry back to the nest to feed and kill the breeding queen and colony members.

Did You Know …

Sanitation programs are meant to reduce or eliminate contamination. But the items and equipment used for cleaning and sanitation can sometimes be the very cause of insect survival. Consider …

  • Brooms and Mops. The bristles on brooms and tentacles on mops are ideal insect-harborage areas. Periodically, bounce the broom head on a clean floor surface and carefully observe what falls out. The bristles retain floor sweepings through static charge, providing a food source for larvae and adults. When these tools are moved from one plant location to another, they inoculate other locations of the plant with insects.
  • Equipment. Another point source of insect contamination and migration throughout a food plant is mobile equipment. Tool carts, forklifts, scissor lifts, and personnel lifts, if contaminated with food dust or debris, provide harborages where larvae and adults can feed.
  • Pneumatic Air. Pneumatic air devices are effective in displacing settled material, but the can also move insect eggs from one location to another. When employing this method of cleaning, make sure that containers, boxes, and product-movement belts are not exposed to dust generated by the air movement. Food particles can be very small, and, when displaced by air, tend to settle out on horizontal surfaces and/or fill small openings in equipment, walls, and floors—making it available to insects.

Developing a checklist to use when conducting an audit or inspection is paramount for reducing potential insect infestations. As new insect harborages are discovered, these areas can be added to the checklist to eliminate repeat offenses.

Extracted from Insect Management for Food Storage and Processing by Jerry W. Heaps (AACC international, 2006). Available from the QA Bookstore (

If the property is grass or gravel, a broadcast granular bait application will work well, but if the plant is surrounded by concrete or asphalt, the bait will need to be put in insect bait stations specifically designed for exterior use, so that the bait is not just sitting on the surface. A tip from Spragins was to put the ant bait in existing rodent bait stations. This not only serves to feed the ants, it keeps them from feeding on the rodent bait.

To reduce the potential of foraging ants moving inside, broadcast treatments should extend at least 10 feet out from the building, Scherer said, but nests that are found farther out also can be individually treated with bait or a contact spray. This is particularly true of species such as fire ants, for which the mounds are generally quite visible.

Bait choice can vary by the identified ant species as well as time of year. This is because different ants are attracted to different foods at different times. For example, Scherer said, when ants are more active in the spring, they will seek proteins and lipids for energy, but as summer wanes and activity begins to decrease, they are more likely to seek carbohydrates and sugars. Thus a bait will be most accepted and effective if it provides the food base the ant is seeking. That said, some ants prefer specific foods regardless of time of year, and just about all ants will be willing to feed on other foods when easily accessible.

However, understanding ant feeding preferences can help in control; if ants are a problem but the bait is not having an effect, it can be advisable to switch to a different base or even type, e.g., solid instead of gel, Scherer explained.

2. Protect the Plant.
Exclusion. “Classic entry points for ants are loading docks, doors, and other exterior openings, such as windows,” Scherer said. Thus, to help keep ants and other pests out, use self-closing doors, air curtains, or other such closures on doors; keep loading docks and areas around doors and windows cleaned and clear of trash and debris that could attract or hide pests; and ensure doors and windows are well sealed and screens are well maintained.

Perimeter Treatment. Applying a band of micro-encapsulated repellent insecticide, labeled for exterior ant use, around the foundation of the structure and entry points not only helps to repel ants, but also, Spragins said, “kills the ones that stumble into it”—keeping the ants from being able to enter the plant in the first place.

Incoming Goods Inspection. Because a manufacturing facility has a lot of raw materials coming into it, this can be a source of infestation of ants, as well as other pests, Scherer said. And once inside, the ants can quickly infest areas, particularly undisturbed sections of warehouse and storage areas. All deliveries should be inspected and those with any sign of pest presence should be refused. Inspecting packaging and other non-food materials is just as important as inspecting food ingredients, as ants (and other pests) will live in and even feed on paper and other products.

3. Minimize Survival.

Even with all these protections in place, there can be times that ants will make their way into the plant through one means or another. Thus, it is critical that practices are put in place to minimize their survival.

“Like any other pest, ants will be looking for food, water and harborage,” Spragins said. “Generally a food plant will offer a lot of opportunity because it has food and moisture.” Thus, the primary means of protecting the plant on the inside is reducing these as much as possible through sanitation.

Virtually all plants have sanitation programs, but there are often overlooked areas, such as spills that are undetected or crumbs that accumulate in undisturbed cracks, that are not cleaned as often as they should be. In some cases, the sanitation process can actually be adding to the potential for pest infestation. Spragins cited plant washdowns as an example. “It is good for washing the equipment, but where does it go after the fact with food in it?” she said. “Pay attention to where the washdown water is going. Make sure you don’t have a buildup of water with food particles.”

Spragins also recommended that cracks and crevices be treated with a biological sanitation product, which reduce organic buildup and smell, which can attract ants as well as other pests. “If you have a lot of ant pressure outside the building, even if food is not there for very long, you can quickly have ants trailing to it,” she said. “Be very careful of sanitation within the plant so you are not building up residue that attracts the ants.”

Spragins also recommended regular monitoring and inspection so as to get a handle on any pest activity early on. Inspection should also include assessment for conducive conditions, such as water sources, scraps and debris, organic build-up, etc.

In some areas of plants, baits can be used, but it is critical to carefully read labels and use only those specifically labeled for the area and the application. Pest management in food plants is significantly different than that for restaurants and other commercial establishments because there are very exacting procedures for what can and can’t be done, Scherer said. Some of these are due to federal regulation; others due to specific standards, such as those for organic foods or specified by retail customers; while others may be policies set by the plant or corporation itself.


The author is editor of QA magazine. She can be reached at