Monitor Soybean for Soybean Tentiform Leafminer

In 2021, the soybean tentiform leaf miner was detected in Minnesota soybean. In 2022, researchers from the University of Minnesota detected soybean tentiform leafminer in McCook, Minnehaha, and Moody counties in South Dakota. The extent of the distribution of this pest in South Dakota is unknown and is currently being investigated. If you observe an infestation of soybean tentiform leafminer in your soybean please contact Adam Varenhorst.

Identification

Small moth with orange, black, and white markings.
Figure 1. Soybean tentiform leafminer moth. (Courtesy: J. Moisan-De Serres, MAPAQ Quebec)

The soybean tentiform leafminer moths are very small at approximately 6-7 mm in length. The wings are held next to the body when at rest and have orange, white, and black markings (as illustrated in Figure 1).

The caterpillars are also very small at 4-5 mm in length. They vary in color based on the caterpillar growth stage from off white to pale-green (as shown in Figure 2-C).

The leaf mining activity of the soybean tentiform leaf miner causes blotch-type leaf mines (Figure 2-A).

Because the mined tissue eventually dies (Figure 2-B), the injury caused by soybean tentiform leafminer is rated the same as defoliation.

Soybean leaf with mined area dying over time. The insect behind the mine is a green caterpillar.
Figure 2. A, B) Leaf mine over time and C) soybean tentiform leafminer caterpillar. (Courtesy: Robert Koch, University of Minnesota)

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