IPM for Ants in Schools


Ants become pests when they invade buildings in search of food or shelter. It is often very difficult and laborious to eliminate most ants from their outside habitat, therefore management should be targeted at preventing ants from invading structures. Unfortunately, prevention is not always successful and control actions must be implemented.

Although ants are often regarded as pestiferous, it should be noted that ants are beneficial in several ways. First, ants are predators of numerous pest insects, including fly larvae and termites. Secondly, ants aerate soil and recycle dead animal and vegetable material thus aiding in the formation of top soil. Additionally, ants are responsible for pollinating plants in some areas. Ants provide a great service to the environment, and management efforts that prevent or control ants are preferred over practices that aim to eliminate ants.

Note that it is not within the scope of this project to address either carpenter ants or fire ants.

Identification and Biology

Ants are social insects that live in colonies whose members are divided into three castes: workers, queens, males. The responsibilities of the worker caste are to enlarge and repair the nest, forage for food, care for the young and queen, and defend the colony. The queen's primary duties are egg laying and directing the activities of the colony while males serve only to mate with the queens.

Ants pass through four stages of development: egg, larva, pupa, and adult. After mating with males, queens lay eggs that hatch into blind, legless larvae. The larvae are fed and cared for by worker ants. At the end of the larval stage they turn into pupae which do not feed. After a short period of time, adult ants emerge from their pupal stage and become worker ants.

The first step in management of pest ants is proper identification. Since there are many types of ants that may invade a structure it is important to identify the type of ant because most ants differ in their habits and food preferences. See Identifying Ants and Common House-Invading Ant Species.

The University of Florida offers a poster that combines line drawings, color and scanning electron microscope photographs in an identification key to help individuals identify the most common structure-invading ants.


Some species of ants such as thief, Pharaoh, and Argentine ants, are particularly prone to infesting food. Inside buildings, these ants are primarily a nuisance since they almost never sting or bite. Since ants walk over many different kinds of surfaces and sometimes feed on dead animals and insects, it is possible that they can carry disease-causing organisms to human food. It should always be assumed that ant-infested food stuffs have been exposed to organisms that can cause spoilage, and the food should be thrown away.

Detection and Monitoring

Visual inspection is the most useful monitoring technique for detecting ants and can be very useful in preventing a developing infestation. A thorough inspection and prevention program is required to locate the ant source.

Management Options

Habitat Modification

The environment should be modified to reduce ant entryways and access to food. With quality materials and careful work, the alteration will be permanent and make a long-term impact on the number of ant invasions.



Sanitation eliminates food for ants. Thorough daily cleaning of school kitchens and food preparation areas is essential.

Proper Food Storage

Physical Controls

At times when only a few ants are noticed foraging in an area, squashing or crushing the ants may be effective.


Detergent Barrier

Temporary "moats" of detergent and water may be useful during heavy ant invasions.

Chemical Controls

At times, non-chemical methods alone prove insufficient to solve the problem. Integrating a pesticide into your management program may be necessary to gain control of the ant problem.

Pesticides must be used in accordance with their EPA-approved label directions. Applicators must be certified to apply pesticides and should always wear protective equipment during applications. All labels and Material Safety Data Sheets (MSDS) for the pesticide products authorized for use in the IPM program should be maintained on file. Do not apply these materials when buildings are occupied, and never apply them where they might wash into drains or sewers.

When treating ants, all baits and dusts should be placed in cracks, crevices, and in precise areas where ants are active. See Tips For Controlling Specific Ants.

Detergent and Water

When ants invade a classroom or food preparation area, use a mixture of soap and water in a spray bottle. This mixture will quickly kill the ants which can then be wiped up with a sponge and washed down the drain. Each classroom, cafeteria, and food preparation area should be equipped with such a spray bottle so teachers and staff can safely deal with emergencies.

Boric Acid

Boric acid is one of the most valuable chemical control tools in an integrated ant management program. It is formulated as a dust, gel bait, and aerosol. It acts as a stomach poison and is relatively non-toxic to mammals. If kept dry, boric acid dust remains effective for long periods of time.

Diatomaceous Earth and Silica Aerogel

These are insecticidal dusts that can be used for ant control. Diatomaceous earth is made from fossilized diatoms, and silica gel is produced from sand. Both kill insects by desiccation; they absorb the waxy layer from the insect's outer covering, which causes dehydration and death. Although these materials are not poisonous to humans directly, the fine dust travels freely through the air and can be irritating to the eyes and lungs; therefore, use a dust mask and goggles during application.

Diatomaceous earth and silica aerogel are especially useful in wall voids and similar closed spaces. During construction and remodeling these dusts can be blown into such spaces, and in finished buildings they can be applied by drilling tiny holes in the walls. These dusts are also useful in crack and crevice treatments.

Some products combine diatomaceous earth or silica gel with pyrethrins. The pyrethrins provide a quick knock-down of the ants, and the dusts provide long-term control.

Ant Baits

Baits greatly reduce the amount of pesticide that must be used to kill ants. Foraging ants take the bait back to the nest to feed to other members of the colony resulting in colony death. Even if the queen is not killed, baits will usually stop an ant invasion. If a colony has been starved by effective sanitation measures, baits will be more readily accepted.

Always place baits out of sight and reach of children, or, if this is not possible, use baits at night or on weekends and remove when children are in school.

Some ants are very susceptible to baits, some are less so. There are many reasons for these differences, only some of which we understand. If you are having difficulty in controlling ants with a bait, the following points may be helpful:

Edited by: Jerry Gahlhoff, University of Florida.
Originally written by: S. Darr, T. Drlik, H. Olkowski, and W. Olkowski

Photographs: University of Florida

Published: April, 1998