The Ants Go Marching One by One

On Feb. 2, we celebrated Groundhog Day, and our furry friend Punxsutawney Phil the groundhog predicted we will have a short winter. For this summer-loving woman, that is a reason to celebrate; however, we won’t mention Phil’s accuracy.  Whether spring comes soon or not, it is a fact that the increased presence of insects comes with this seasonal change. Among those insects are ants. Different species of ants are present in different regions across the United States.

First, let’s cover ants generally. Ants are some of the most prevalent pests in households. They are found in homes and restaurants, hospitals, offices, warehouses, or any building where they can find the necessary means of survival (food, water, and shelter). There are over 12,000 species of ants around the world, approximately 1,000 species within North America, but only about 21 species of ants are considered pests. Along with bees and wasps, ants are in the order Hymenoptera.

Ants, wasps, termites, and bees are what are known as social insects. Being social, or sociality, is defined as a group of individuals of the same species exchanging information and cooperating in one way or another. The key to this cooperative living is communication. The word communication is derived from the Latin word communis, which translates as "to exchange or share obligations." That is precisely what these social insects do: they share information on where to eat, what to eat, dangers to avoid, potential mates, etc. Many interactions in the insect community demonstrate characteristics of sociality; however, not all insect gatherings are considered "social." Often, a large group of insects indicates a response to an environmental stimulus, either positive or negative. 

Ants are considered eusocial, meaning they are entirely social: every member of the colony works together in cooperative brood care, there are overlapping generations, and there is a division of labor. Every member of the colony has a job and is responsible for something within the colony. Ants reproduce in several different ways. They can reproduce by budding, where workers leave to start new colonies, or swarming, where new unmated reproductives leave to mate and form their own colony. 

Knowing about ant biology and habitats and being able to investigate the source of ant pests is vital to our success in managing them. When I was younger, the Nancy Drew books were some of my favorites as I loved trying to identify who did what and solve the mysteries. To this day, crime procedural shows tend to be a favorite of mine. Similarly, one of the things I love about pest control is the investigative aspect. That is the whole premise of Integrated Pest Management: understanding a situation fully so that we can make a proper management plan for the pest at hand. In our own investigations, we must undertake these four things to be effective in ant management: 

1. Identify the ant. Ant ID may be the most important thing that can be done in ant control. And perhaps one of the hardest.  There are several species of ant species that are considered pests, and most are quite small. The first step would be to use some kind of microscope or handheld spyglass to get a really good look at the ant in question. Things to note when looking at ants would be first to observe how many nodes they have. The node is the small projection on the petiole, which is the small waist-like area between the thorax and the abdomen. Some ants will have one node and others will have two. Most aggressive species of ants such as fire ants have two nodes, and ants like odorous house ants have one. Each ant’s nodes are different shapes; some are more rounded while others are more sharply pointed. Alternatively, some nodes, such as those found on the odorous house ant, can be slightly hidden by the thorax. Another identifying characteristic of ants is their antennae, which can have district numbers of segments on them depending on the species. Color and size are not the best identifying characteristics but can sometimes be helpful when observed with more helpful characteristics such as nodes and antennae.

2. Follow the trail. A great way to find a nest would be to follow the trail. There is truth in the song “Ants Go Marching One By One” as ants will trail to and from their nest to forage for food. However, they don’t always march “one by one.” They sometimes have trails that are not necessarily single file but rather several individuals trailing together. For these ants, the trails look much thicker in size. This is characteristic of the odorous house ant. The Argentine ant, which is often confused with the odorous house ant, can be differentiated from the odorous house ant because their trails are not as thick. Argentine ant trails more often appear single file with ants quickly trailing back and forth from the nest. Finding ant trails and observing how ants are trailing helps us find nests.

3. Identify nesting habits. Once we know which ant species we are dealing with, we can better understand where it is nesting, which will be vital to proper treatment. Some species of ants will nest within the home, others outdoors, and some both indoors and outdoors. There are some that will have multiple nesting locations and others with a single nest. For example, odorous house ants can be found both indoors and outdoors, but their preference is outdoors. And when we discover ants with multiple nests, pharaoh ants reproduce through the aforementioned budding process, in which some ants will “bud” off of the nest to create a new nest which will be extensions of the original one.

4. Treating ants. Now that you know which ant is an issue, how it's trailing, and where it’s nesting, it’s time to make an informed decision on how to treat the nest in question. Generally the reason for identifying the ant is to follow the trail and find the nest or nests. This is important because the two best methods for controlling ant colonies is baiting and treating the nest. We use bait so that the foraging ants will find it and then bring it to their colonies. Baits take advantage of a practice known as trophallaxis, which is the sharing of resources within a colony. So the foraging ants will eat the bait and share it with the other colony members, leading to what will hopefully be colony elimination. However, another method would be to directly treat the nest with liquid or dust. This is why understanding what ant species is present and its nesting habits is so important. Because if we only treat one nest of a species of ant that may have several, then we have only treated a portion of the problem. 

As the old adage goes, “knowledge is power,” and that holds true for ant control as well. Knowledge is the most important tool we have in our IPM tool belt. Understanding the ant species present, how it trails, and where it nests will help us properly control ant problems. As pest control professionals, we want to help protect our customers' homes and property so that they can enjoy their home (and snacks!) without any extra company.