While scouting soybean this week, we came across a unique caterpillar in the upper soybean canopy. At first glance, the feeding behavior of rolling leaves with silk webbing resembled that of the thistle caterpillar. However, upon further examination, the culprit was identified as the obliquebanded leafroller.
Obliquebanded leafrollers are relatively small caterpillars with light to dark green colored bodies. In addition, they have a dark brown to almost black head capsule with a dark brown to black segment directly behind the head. They also have black true legs and four pairs of abdominal prolegs (Figure 1).
Figure 1. Obliquebanded leafroller caterpillar. Courtesy: Adam Varenhorst
Obliquebanded leafrollers feed on a wide variety of hosts, including soybean. Typically, these caterpillars are more associated with plants in the Rosaceae family (e.g., apple, peach and pear). In all of our observations, there was only one caterpillar per plant, and the defoliation associated with these caterpillars appears to be limited to just one or two leaves per plant. The older caterpillars use a silken webbing to roll the leaves that they are feeding on (Figure 2). Although these caterpillars alone are not cause for concern, cumulative defoliation should be monitored this time of year with a threshold of 20% defoliation throughout the field.
Figure 2. Obliquebanded leafroller caterpillar with silken webbing on soybean leaves. Courtesy: Adam Varenhorst