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The soybean tentiform leafminer has been found in 51 counties in Minnesota, North Dakota and South Dakota

By Arthur V. Ribeiro (Post-doctoral Associate) and Robert L. Koch (Professor & Extension Specialist), Department of Entomology, U of MN

Since its first detection feeding on soybean in the United States in 2021, we have been keeping a close eye on this potential new pest, which now has an official common name: the “soybean tentiform leafminer”. The soybean tentiform leafminer (Macrosaccus morrisella) is a tiny moth native to North America where it has been known to feed on two native plants: American hog peanut and slickseed fuzzybean. However, it has recently developed the ability to feed on and infest soybean. Survey efforts have expanded to determine how widespread are the infestations of this insect in soybean.

In 2021, soybean tentiform leafminer was detected in the Twin Cities Metro Area, in Ramsey and Dakota counties. In the following year, we received 12 new reports extending from the Twin Cities Metro Area to southeast South Dakota. These new reports raised concerns about the actual geographical distribution of this pest in soybean. Therefore, a wider survey was conducted during the summer of 2023 with collaborations between the University of Minnesota, the Minnesota Department of Agriculture, and North Dakota State University. In 2023, soybean tentiform leafminer was found in 77 fields across 44 counties in Minnesota and North Dakota. From 2021 to 2023, soybean tentiform leafminer has been detected in 51 counties in Minnesota, North Dakota and South Dakota (Figure 1).

Figure 1. Occurrence of soybean tentiform leafminer (STL) in soybean fields in Minnesota, North Dakota, and South Dakota since first detection during the summer of 2021 to November 2023.

Within fields, infestations of soybean tentiform leafminer appear to occur predominantly along field edges close to tree lines. Heavy infestations at field edges of soybean fields have been detected in south-central Minnesota in 2022 and 2023.

The adults of the soybean tentiform leafminer are tiny insects and unlikely to be observed in the field. Injury to soybean leaves is caused by the immature stage (larvae). The larvae feed inside soybean leaves, forming mines that are initially visible on the lower surface and, eventually, also from the upper surface (Figure 2).

Figure 2. Progression of mines (leaf injury) from soybean tentiform leafminer on soybean leaves. The mines get larger as the larvae grow and feed more within the leaves (photos by R.L. Koch).

Research on various aspects of the biology and management (e.g., chemical control) of this pest is underway. Updates on this research will be posted as projects are completed.

Contact us…
We are looking for additional fields for sampling and research on soybean tentiform leafminer. If you notice soybeans with injury resembling that of the soybean tentiform leafminer (Figure 2), please contact Bob Koch ( or Arthur Ribeiro (

For more information:

We are especially grateful to Angie Ambourn and Chelsey Penuel and their staff with the Minnesota Department of Agriculture; Angie Peltier and Anthony Hanson and their staff (Amelia Landsverk and Katie Olson) with the University of Minnesota Extension; Janet Knodel and Patrick Beauzay and their staff with the North Dakota State University IPM Crop Survey, and Fabio Fuhr and Gabryele Ramos from the Koch lab for assistance performing the field surveys for this pest.

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