Early Frost or the Bermudagrass Stem Maggot?


   Yellow or brown bermudagrass tips that look like the result of unseasonal frost damage (Figure 1) could be a symptom of attack by the bermudagrass stem maggot. The larvae of this tiny fly, a native of Asia, have been damaging bermudagrass pastures and hayfields across the South since 2010. The insect and its characteristic damage were found in several Allen County fields in 2013, but no infestations were reported in the state during 2014. However, Steve Osborne, Allen County Agriculture and Natural Resources Extension agent, reported infestations in several fields late last week.
   The larval or maggot stage of the insect bores into the upper portions of tillers (Figure 2). Shoots beyond the damage die (Figure 3).  Damage varies with the growth stage of the grass; numbers of flies present, which increases during the summer; and drought stress.
   • Bermudagrass fields should be checked regularly for damage from now until frost.
   • Consider control if more than 20 percent of plants show dead tips.
   • Early harvest with removal of baled grass, if practical, is a good management alternative.
   • Application of a labeled insecticide within 7 to 10 days of harvest of an infested field can cut down on re-infestation by later generations of the fly. ∆
   DR. LEE TOWNSEND: Extension Entomologist, University of Kentucky

Figure 1. Frosted appearance of bermudagrass due to boring 
by stem maggot.

Figure. 2. Split infested stem showing shredded tissue and waste 
material produced by the stem maggot.

Figure 3. Close-up view of stem maggot injury showing dead tip. 

Figure 4. The bermudagrass stem maggot fly is 1/8 inch long with 
a light gray thorax and an abdomen that is yellow with some 
distinct dark spots.                                                        
Photos: Lee Townsend, UK

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