Green Cloverworm In Large Numbers Spotted In Union County

PRINCETON, KY.
   Ms. Amanda Martin an Extension Associate working with the UK Soybean Verification Program, has noticed some unusually large populations of green cloverworms in Union Co. KY. These populations are not yet at economic levels, but they are large enough to bear watching. Producers, consultants and agents are warned to keep an eye on these pests over the next month to six weeks. It is NOT a foregone conclusion that this will be an economically important pest, but should not be ignored.
   Green cloverworm larvae are slender and light green caterpillars with three pairs of white stripes running the length of the body. They have three pairs of legs near the head, three pairs of fleshy legs near the middle of the body and a single pair of fleshy legs at the tail end. These caterpillars are often parasitized or diseased. Parasitized larvae will have small eggs on their body, often near the head. Diseased larvae may appear watery and have sluggish movement, or be covered with fungal growth.
   Green cloverworm feed extensively on soybeans. Young larvae skeletonize the undersides of leaves. Older larvae eat all the leaf except the largest veins. Economic thresholds for this pest were developed on wide row (30”) beans, which we generally do not use in Ky. However, one can use the soybean defoliation tables that are found in either the KY Integrated Crop Management Manual for Field Crops-Soybeans, IPM-3, found at http://www.uky.edu/Ag/IPM/manuals.htm or the Insecticide Recommendations for Soybeans – 2011, ENT-13, found at: http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html. These publications are also available through your county extension office.
   These insects are not difficult to control with insecticides. Any of the products listed in the above insecticide recommendations should be adequate to the job. Like most other insect pest management decision in KY, the more important decision is not what to spray, but IF to spray. Δ
   DR. DOUG JOHNSON: Extension Entomologist, University of Kentucky

Figure 1. Green cloverworm caterpillar. Note the three pair of fleshy legs (prologs) near the center of the body. Most other soybean feeding caterpillars have four pair, and a few have two pair.