Distribution Impacts Control

There are about 3,600 different species of mosquitoes in the world that have been identified. Some mosquito scientists (a.k.a. “culicidologists”) estimate the actual number may be twice this number. Some species are common while others are comparatively rare. They are found in all types of environments, from snow-capped mountains to harsh deserts to salt marshes to customers’ yards. All mosquitoes require water to complete their life cycle and they will breed in almost anything that will hold it, from a bottle cap to an abandoned swimming pool and everything in between.

The goal of this article is to address that mosquitoes are not distributed randomly. There are many key factors that influence mosquito distribution, including availability of water, biodiversity of suitable habitats, hosts to feed on, environmental factors (especially temperature and humidity), shelter from adverse environmental conditions and others.

U.S. DISTRIBUTION. To illustrate these points, let’s take a look at North America, specifically the continental United States, where we find approximately 175 species. Across the lower 48 states, the number of species per state varies widely (see Figure 1). Remember that these numbers are close estimates, and that more research and control has been done in some states than in others, so we know more about the mosquito populations there.

Texas leads the way with approximately 85 species, followed by Florida (80) and New York (70). The fewest number occurs in West Virginia (35). In 34 of 50 (68 percent) of states, the range is between 50 and 69 species (see Figure 2). The differences are in large part driven by the amount of biodiversity — the variety of life and habitats — within each state. The greater the biodiversity, the more types of habitats are available for mosquitoes.

So, mosquitoes are NOT randomly distributed across the United States, nor within an individual state. This principle also applies to the properties of your accounts, whether they are commercial or residential. Why? Adult mosquitoes are fragile creatures and are subject to dessication (drying out) and death if overexposed to harsh environmental conditions. Whether they are resting, feeding on plant juices or, in the case of the female, developing eggs, male and female mosquitoes will seek areas that provide some protection from the elements.

Fig. 2. Mosquito species by number of states. (Image courtesy of Catchmaster)

 

THE BIG 4. Where will mosquitoes hang out? They are found primarily in the “Big Four” locations: cool, shaded, moist and out of the wind. And remember, we are talking about very small differences in these microclimates, which mosquitoes can easily sense. Typical habitats are shaded vegetation; under decks, sheds, and tarps; inside used tires, treeholes and buildings; crawlspaces; animal burrows; under bridges and overpasses; and under eaves and overhangs of buildings and patios.

When you are performing your inspections for mosquitoes, use the “Big Four” to guide where you look but please remember that mosquitoes don’t read our textbooks so it is imperative to inspect the entire property for breeding sites. If you decide to apply a mosquito adulticide as part of your service, do so according to the label directions and target areas reflective of the “Big Four.” In doing so, you will not only kill more mosquitoes but you will also save time, money, use less product, and better protect the environment and the pollinators. Oh, and most importantly, you are much more likely to keep your customers satisfied! Happy hunting!

Editor’s note: In order to create Figures 1 and 2, the authors used at least two references per state for the estimates of number of species present. Sources included websites of state health departments; mosquito abatement districts and professional organizations; scientific publications and technical articles; university resources; individuals working in mosquito research and control; and a few miscellaneous sources.

Authors’ note: Thanks to the Catchmaster marketing/graphic design team for their support on this project.

Stanton Cope is vice president, Technical Products and Services, Catchmaster (AP&G). Amyanne NK Cope is an infectious disease epidemiologist.