Insect or Pest? Identifying Springtime Threats

With the onset of spring, we can anticipate ringing phones and frantic would-be or current clients calling with a concern or pest problem. As pest management professionals, I believe we have an obligation to be more knowledgeable about insects and other arthropods than our clients and customers. Many customers and clients will, in fact, link quality service to the knowledge of the PMP they are working with.

It is important to first understand, if you didn’t already, that insects, as a class of animals, far outnumber all other living animals on the planet. In fact, there are three times as many insects on earth as there are other animals in the rest of the animal kingdom, and there may be millions more yet to be discovered. Generally speaking, we divide and group insects by their importance to humans.

INSECTS VS. PESTS. First, there are species that are not considered pests. Surprisingly enough, this group represents close to 99 percent of all insect species. Next, there are beneficial insects. Beneficial insects extend far beyond the well-known honey bees, which pollinate roughly 80 percent of the earth’s plants. Beneficial insects also include species such as ladybugs and praying mantids, which are predators of insect pests. Lastly, there are the pest insects. This group accounts for the smallest number of species. These species may feed on plants, cause injury, transmit disease or cause structural damage.

While pest insects are the primary concern for the PMP, it is important to know how to delineate between these groups to determine when and how to act. To some consumers of pest management services, they are all just “bugs,” and therefore pests. This misunderstanding may be accompanied by broad assumptions that our role as PMPs is to simply “kill bugs.” A lot can go wrong if this sentiment is upheld by a PMP, such as pesticide exposure to non-target organisms and the environment.

THE PMP’S ROLE. Your role as a PMP is not one of a killer, or that of a pesticide applicator, but more so to be steward of the environment and to protect and defend both public and environmental health. Knowing the difference between an insect and a pest and when to act is an important facet of that role and responsibility. To better understand your role as a PMP, someone more knowledgeable about insects and arthropod pests, let’s look like at some lesser discussed springtime insects and determine which are pests, which are not, and how to respond accordingly.

Before we go further, I want to share my own general rule of thumb when considering when to act. I, like many of you reading, am a structural PMP and entomologist, meaning that my particular licensure (and knowledge) is only applicable in many instances to pests in, on, under or immediately adjacent to a structure. So, if and when I am presented an off-structure challenge (e.g., garden pests), while I may be able to identify the pest (or insect), I may not legally be able to provide a service or solution. Make sure you head into the season knowing your state’s licensing requirements for structural, turf and ornamental pesticide applications

THE GREEN LACEWING. Mostly commonly observed feeding and flying around grasses, shrubs and other ornamental plants, this beneficial insect may occasionally fly into or land to rest on a structure. This insect is neither a structural nor an ornamental pest and requires no action on the part of the PMP (except customer education). Green lacewings are beneficial insects that feed upon aphids and other insects that may harm plants.

PRAYING MANTIDS. To clarify confusion, we often hear “praying mantis,” but mantis refers to the genus Mantis. Only certain praying mantids belong to this genus. Mantid refers to the entire group. Owing to its large size (often greater than two inches) and characteristic enlarged, spined femurs, the sight of a mantid that has found its way onto a structure may elicit a call to action from a customer. These insects are of no concern for the PMP or your client. In fact, these beneficial insects are ferocious predators that may prey on pests such as beetles, moths and flies. While some may become brutal hunters and eat butterflies and bees, their benefit far outweighs any perceived risk to other organisms.

GROUND BEETLES. Ground beetle is a loosely interpreted name that we often use in reference to the beetle family Carabidae, of which there are some 1,700 known species in North America alone. Although not typically seen inside structures until mid-summer, sightings of emerging overwintering adults in mulch and flower beds abutting a structure are common in spring. These beetles cause no structural damage, nor can they breed (infest) indoors. Ground beetles are considered beneficial insects, as both the adults and larvae are predacious of other arthropod pests including slugs, nematodes, weevils and silverfish.

Ground beetles may be perceived as a structural nuisance pest if they breach a structure. If spotted inside a structure, they may be incorrectly identified as cockroaches due to color and size. The question then is, to act or not to act? Making this decision is situational, and the decision should be informed by client tolerance and context. By this, I am referring to instances in which the beetles have been found, and in what numbers. For example, one beetle found inside a residential sunroom may be tolerated, whereas 10 found inside a processing area of a food manufacturing facility may prompt action.

LADYBUGS AND ASIAN LADY BEETLES. No, the two are not the same, and it is important to be able to tell the difference between them. They certainly look similar at first glance; however, there are some key differences between the two. Asian lady beetles are slightly larger than ladybugs. Coloration between the two varies. Ladybugs often present bright red with black spots, and their heads tend to be black with small white “cheeks,” while Asian lady beetles can vary from red to orange, and they may present with or without spots on their wings.

Ladybugs are beneficial insects, as they are natural enemies of aphids and other sap feeders. Asian lady beetles, on the other hand, can pose a nuisance threat when they congregate on structures in large numbers, although this typically doesn’t occur until later in the season. If you are seeing Asian lady beetles in or on a structure in the spring, it is more likely that they are leaving their comfortable overwintering harborage to head back outdoors, in which case an insecticide application to the structure is going to be of little value.

PUTTING IT ALL TOGETHER. The takeaway from this is that it is important for PMPs to have a solid understanding about insect and pest identification and the ability to identify both in context. While this list is miles away from being all-inclusive, its purpose is to serve as an example that not all insects are pests, and your role as a PMP is not to “kill bugs.”

Hopefully, after reading, you will be encouraged to learn more and think more critically in the field this spring when you encounter an insect or other arthropod that either you or a customer are unfamiliar with. Is it a friend or is it a foe? If you don’t know, ask for help or research it. Just follow the basic tenets of IPM: inspect first, identify, evaluate the threat(s) and craft an informed solution. Keep in mind that client education regarding beneficial insects may be all that is needed and can serve as the best solution in many instances.

Timothy P. Best, A.C.E., B.C.E., MSPH, began his pest management career as a commercial technician in 2005 after serving in the U.S. Air Force. He now serves as a technical manager for Terminix. He is a member of the Entomological Society of America, the American Association of Pesticide Safety Educators, Pi Chi Omega and the American Public Health Association.