Soybean thrips are small, slender bodied insects that are less than a couple mm in length. They belong to the order, Thysanoptera meaning fringe winged. (thysanos=fringe, pteron=wing). Having modified mouthparts, thrips rasp and puncture plant cells to suck up oozing plant sap. The physical feeding injury caused by thrips to soybeans rarely causes economic losses with the exception of when thrips populations are extremely high and plants are drought stressed. Thrips feed on the underside of leaves, typically along leaf veins causing pale colored scars. Under heavy feeding pressure, the leaves can appear mottled between the leaf veins and the leaves may become wrinkled. Soybeans are more susceptible to thrips injury during early season growth stages (VE-V6).
Thrips feeding injury
Thrips are also a concern in many crops because some species are known vectors of plant diseases. Soybean Vein Necrosis Disease (SVND), for example, is a relatively new thrips-vectored virus that was recently detected in Delaware and Maryland that affects soybeans.
Soybean Vein Necrosis Disease Symptoms
For more information on SVND, please review Guess the Pest Week #20 http://extension.udel.edu/weeklycropupdate/?p=11055
Here is a link to our 2016 Soybean Vein Necrosis Disease Survey Results: https://cdn.extension.udel.edu/wp-content/uploads/2015/10/06094029/SVNVSURVEY2016-FIN-2-1.pdf
Here is a link to a poster presentation on the Occurrence and impact of Soybean Vein Necrosis Disease in Delaware: https://cdn.extension.udel.edu/wp-content/uploads/2015/10/06094710/Occurrence-and-Impact-of-Soybean-Vein-Necrosis-Disease-in-Delaware.pdf
Fun Entomology fact: Thrips is used in both the singular and plural form meaning that you can either have one thrips or many thrips.