Switchgrass Top-Node Borer

                                                                                                                                                                                                                              Last modified 03 September 2009
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Presently an unidentified pyraloid, possibly belonging to Crambidae.

This interesting caterpillar was found abundantly in the distal two internodes and base of the rachis of switchgrass.  The larvae live in the hollow internode areas and feed on the cell layers lining the internode, but especially feeding at the meristematic tissues at the internodes.  Boring through the internodes is typical.  Feeding is also done in the basal regions of the rachis of the inflorescence.  Typically, there is a small entry/exit hole at the base of the penultimate internode and immediately above the node.  Stem occupancy (= infestation?) can be diagnosed by a characteristic pale-colored flagging, where the terminal internodes, leaves, and inflorescence are light brown in color.  Commonly, the inflorescence is not fully extruded, but does not have the "witches broom" effect seen when Chilophaga midge larvae are in the stem.

This species is not confused with the Switchgrass moth that has the larvae feeding in the proaxis and first elongated internode during the winter and spring.