Invasive scale insects cost U.S. agriculture at least $4–8 billion each year, yet true losses remain poorly tracked. For scale insects and beyond, an accounting of these losses is a major blind spot that complicates pest control, policy decisions, and efforts to protect food production. Among many invasive scale insect species in the U.S. are Heliococcus summervillei (left), Phenacoccus miruku (middle), and Crypticerya genistae (right). (Photos by Erin C. Powell, Ph.D.)

By Scott A. Schneider, Ph.D., and Erin C. Powell, Ph.D.

Erin C. Powell, Ph.D.

Scott A. Schneider, Ph.D.

The saying goes that money doesn’t grow on trees. That is unless, of course, you farm crops—in which case, most of your money grows on trees (or shrubs, or grasses). If you farm crops, the amount of money you earn depends on how much can be grown and sold.

But, inevitably, you compete with pests and diseases in a dynamic environment, where new invaders may become established, or shifting abiotic conditions may promote explosions in pest populations. As a result, you’re faced with diminishing crop yields. Now perhaps you’re also buying more pesticides, investing more in biological control, and spending time consulting with extension agents to look at your agronomic practices.

There’s no denying that farming is hard and uncertain work. Yet agricultural production (the money grown from trees) is so critical to our survival that, surely, society must keep very close tabs on the economic costs associated with invasive pests and diseases.

Right?

Let’s consider production losses due to herbivorous insects. Whether directly, through herbivory, or indirectly, through disease transmission, invasive insects are responsible for intense resource competition and substantial losses to agricultural production. Look at Florida’s citrus industry for example, and the dramatic 79% drop in production in recent years, relative to the early 2000’s. This is due largely to citrus greening disease, also known as huanglongbing, a disease vectored by an invasive species of psyllid, Diaphorina citri, which became established in Florida around 2005 (Singerman and Rogers 2020; Cruz et al. 2023) . The hit to Florida’s citrus industry amounts to billions of dollars and the loss of thousands of jobs.

OK, so, how much monetary loss to agricultural production, to the producers and the consumers in the system, can be attributed to invasive insects each year? Would it surprise you to learn that no one has a good answer to this question? It’s many billions of dollars, hundreds of billions perhaps; that much is clear (Pimentel et al. 2005; Bradshaw et al. 2016; Naranjo et al. 2019) . But investigators who aim to get at the heart of this matter and report specific dollar figures ultimately find there is scant information out there to draw upon when formulating estimates.

In putting together our article published in March in Biological Invasions on the impact of invasive scale insects on agriculture, we were hard-pressed to find documentation of economic figures attributable to the level of species, let alone to family, super-family, or even order. And we struggled to identify agencies (at the federal, state, or local level) tasked with collecting, quantifying, and reporting such impacts in detail. From the scarce information we could find, it’s clear that scale insects have substantial impact on agriculture and consumers. Our minimum estimate is $4–8 billion lost annually due to invasive scale insect pests in the United States alone. For the world at large, one can only guess.

Our study also highlighted that biosecurity efforts in the United States are working to reduce the rate of unintentional species introductions. As the volume of horticultural imports to the U.S. increased by 1005% between 1967 and 2024, the rate of new scale insect species introductions remained steady. Yet these practices are not perfect. About one new scale insect species has become established per year in the United States over the past 20 years; looking back even further, this pattern has held since about the 1930s.

Why the focus on scale insects? This diminutive group receives little attention but, despite only having about 8,600 described species (far less than 1% of all described insect species), it represented a disproportionate 12% of all insect interceptions at ports of entry in recent years by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service. More than half of non-native scale insect species are polyphagous, which concerns our diverse national agricultural industry. Moreover, some invasive specialist species are troubling, such as Heliococcus summervillei, sometimes known as the pasture mealybug, reported new to the U.S. in the fall of 2025, and causing dramatic die-back of pasture grasses and sugarcane in Texas and Louisiana.

Entomologists are often asked, how much does [your focal taxon] cost agriculture, or how important are they to agriculture? Would you be able to answer for your group? It’s difficult to effectively communicate and justify investment in research or phytosanitary measures to reduce the flow of invasive species when we have inadequate estimates and a narrow view of their true costs. How do we justify spending more money to save money? And if we aren’t even crunching the numbers on how much invasive species cost agriculture, are we close to capturing their ecological costs?

Our study highlights the impact of scale insects on U.S. agriculture, but it also points to something more consequential: the conspicuous absence and dire need for better reporting and data-driven estimates of the economic impact of invasive pests.

Scott A. Schneider, Ph.D., is a research entomologist at the USDA Agricultural Research Service’s Systematic Entomology Laboratory and curator of Coccomorpha at the Smithsonian National Museum of Natural History in Washington, DC. Email: [email protected]. Erin C. Powell, Ph.D., is a research scientist at the Florida Department of Agriculture and Consumer Services in Gainesville, Florida. Email: [email protected].