Non-native scale insects (Hemiptera: Coccomorpha) of the United States and their impact on U.S. agriculture

Authors: Schneider, Scott; POWELL, ERIN - Florida Department Of Agriculture And Consumer Services

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2026
Publication Date: 3/30/2026
Citation: Schneider, S.A., Powell, E.C. 2026. Non-native scale insects (Hemiptera: Coccomorpha) of the United States and their impact on U.S. agriculture . Biological Invasions. 28:85. https://doi.org/10.1007/s10530-026-03784-9.
DOI: https://doi.org/10.1007/s10530-026-03784-9

Interpretive Summary: Scale insects are highly invasive pests of agricultural crops and ornamental plants. They are frequently encountered in plant quarantine at ports of entry to the United States, accounting for 12% of all insects intercepted at ports in 2021–2023. In high densities, scale insects negatively impact plant health and reduce crop yields. About 27% of scale insect species in the United States are non-native and have been introduced through trade and other human activities. Despite the enormous economic impact of invasive insects, appraisals of their cost to agriculture remain grossly underestimated and information on costs is under-reported. Drawing information from various sources, this study estimates that scale insects cost U.S. agriculture upwards of $8 billion dollars annually; a conservative estimate of their global impact on agriculture is $16 billion annually. About 1 new scale insect species becomes introduced to the United States per year, a pattern that has held steady since the 1930s after national plant quarantine laws were enacted. Over the last several decades the volume of horticultural imports to the U.S. has increased dramatically, but there has not been a proportionate increase in the number of new scale insect introductions, illustrating that quarantine measures are effective at preventing and delaying species invasions. In recent decades, most new species have been introduced to the United States through Florida, highlighting a high priority focal region for enhanced prevention. Major commodities impacted by scales include citrus, cotton, grapevine, stone fruits, and common ornamental plants among many others. This article provides details on the species involved, commodities impacted, and invasion patterns, information that will be valuable to state and federal regulatory agencies, producers, and scientists in the fields of systematics, biocontrol, forestry, and conservation.

Technical Abstract: Scale insects are ubiquitous herbivores that are frequently transported on plants through horticultural trade and are encountered at ports of entry worldwide. We provide an update on the non-native species of scale insects that have been introduced to the continental United States including: the species involved, their host associations, pest status, introduction rates, invasion pathways, and we estimate their economic impact on U.S. agriculture. There are 1,098 species of scale insects recorded in the continental U.S., 296 are non-native species (27%). Introduced species belong to 16 families, the most common of which are Diaspididae (150), Pseudococcidae (62), and Coccidae (44). These species are often pests; 215 species (73%) are minor to major horticultural pests or are recently introduced and have the potential to become pests. Over half (56%) of introduced scale insects are polyphagous, able to survive and reproduce on many host plant families, and the most impacted commodities include deciduous and tropical fruiting trees (e.g., apple, banana, citrus, grapevine, stone fruits), landscape and ornamental plants (e.g., exotic trees, shrubs, palms, roses), grasses (e.g., ornamentals including bamboos, cereal grain crops, sugarcane), houseplants (e.g., cacti, orchids, snake plants, succulents), trees (e.g., conifers and hardwoods), and miscellaneous other commodities (e.g., cut flowers, cotton, coffee). Scale insects are estimated to cost U.S. agriculture and consumers as much as $8 billion USD annually in production losses and management costs. We discuss the impact of plant quarantine measures and expectations about future species introductions.