Statewide Slug Monitoring Project

Slugs are increasingly concerning for Ohio growers, especially in no-till fields where cover crops are grown. Slugs are a nocturnal pest that feed directly on soybeans causing both seed and foliar damage that can result in complete loss of the plant (Figure 1). Because slugs feed at night, growers often don’t notice until the damage has already occurred, and it is too late. To better manage slugs in Ohio, we first need to understand slug pressure across our state. To do this, 19 counties in Ohio are participating in a multi-state project funded by the United Soybean Board to monitor slugs in soybean fields across the region. Each field will be monitored using shingle traps for 9 weeks (3 weeks before plant, and 6 weeks after plant) (Figure 2). Shingle traps consist of a 1-sq.ft. white roofing shingle secured to the ground with tent stakes. These traps provide a refuge for slugs to hide under during daylight. Each week, traps are checked in the morning by lifting the shingle and counting the number of adult and juvenile slugs underneath each trap. The data collected from this study will allow us to have a better understanding of the slug variations in Ohio and across the region.

Figure 1. Slug feeding on soybean cotyledon in the field.   

Figure 2. Shingle trap placed in the field.

Certain field criteria were considered when selecting fields to deploy the shingle traps including: a no-till field that will be planted to soybean in 2024. Additionally, no foliar applications of insecticide should be applied, and no slug bait applied within 10 feet of the shingle traps. With this in mind, fields were selected across the state by Extension Educators and shingle traps were deployed from April 8^th – May 8^th. Variability in the trap deployment date is due to the anticipated planting dates at each particular site, since traps are requested to be monitored 3 weeks before plant, and 9 weeks after plant. The figure below shows the average number of slugs found under the shingle trap in each county from May 13^th – 19^th (Figure 3). Overall, majority of counties are reporting low number of slugs found under the shingle traps. Seneca had the highest average number of slugs (7.5) followed by Wayne (1.9).

Slugs in Ohio

May 13^th – May 19^th 

Figure 3. Average slugs captured from May 13^th to May 19^th. The bold number on the left indicates the average slug count for the week, followed by the standard number on the right which indicates the total traps set up in that county.