Location: Temperate Tree Fruit and Vegetable Research
Title: How many kinds of pear psyllids are there? And where did ours come from?Author
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Horton, David |
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Submitted to: Internet Web Page
Publication Type: Other Publication Acceptance Date: 12/22/2025 Publication Date: 1/9/2026 Citation: Horton, D.R. 2026. How many kinds of pear psyllids are there? And where did ours come from?. Internet Web Page. https://treefruit.wsu.edu/. Interpretive Summary: Pear psylla is the key insect pest in pear orchards of the Pacific Northwest. The pest is native to Europe, entering North America through the northeastern U.S. as a hitchhiker on pear stock from Europe. Entry occurred in the early-1800s, or a full century before the pest’s arrival in the Pacific Northwest. What may not be fully appreciated is that the North American psyllid is but one member of a large complex of pear psyllids that spans the region between Western Europe and Eastern Asia. Size, color, geography, and lifecycle vary among species. Pear psylla is the sole member of this group to have made it to North America. A surge in the importing of pear trees from Western Europe in the early-1800s led to psylla’s entry into the US. This article examines these events. One conclusion to emerge is that pear psylla – with one other species of pear-associated psyllid – is the only pear psyllid to have had the right mix of biological traits and European geography to make that early-1800s transatlantic jump into North America. Technical Abstract: Pear psylla is the key insect pest in pear orchards of the Pacific Northwest. The pest is native to Europe, entering North America through the northeastern U.S. as a hitchhiker on pear stock from Europe. Entry occurred in the early-1800s, or a full century before the pest’s arrival in the Pacific Northwest. What may not be fully appreciated is that the North American psyllid is but one member of a large complex of pear psyllids that spans the region between Western Europe and Eastern Asia. Size, color, geography, and lifecycle vary among species. Pear psylla is the sole member of this group to have made it to North America. A surge in the importing of pear trees from Western Europe in the early-1800s led to psylla’s entry into the US. This article examines these events. One conclusion to emerge is that pear psylla – with one other species of pear-associated psyllid – is the only pear psyllid to have had the right mix of biological traits and European geography to make that early-1800s transatlantic jump into North America. |