Chinch Bugs in Florida Lawns

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During the hot summer months in Florida we often receive questions regarding dead brown patches in St. Augustine lawns. It is often incorrectly assumed, since our summers are so wet, that fungus is to blame. Most residents are unfamiliar with the following symptoms of a chinch bug infestation.

Chinch bugs are tiny, about 1/10 to1/8 inch long (Chinch bug pictured above).  They often scurry out of sight when the grass is disturbed, making them difficult to spot. Chinch bug damage usually appears first in hot sunny areas as small brown areas that gradually enlarge as the bugs move out of dead spots and into green turf, especially in grass that has been over-fertilized and contains more thatch.  At this stage it is recommended that the chinch bugs be spot treated with a pesticide specifically labeled for chinch bugs.  When spot treating, always treat a 10 to 15 ft. buffer area around the affected turf rather than blanketing the entire lawn with pesticide.  Be sure to follow label directions when using any pesticide.

Most populations of chinch bugs have developed some level of resistance to most homeowner pesticides making a single application ineffective.  Additionally, chemicalsthat are effective against chinch bugs do not kill the Chinch Bug eggs so a new population may emerge anytime up to 6 weeks after application of a pesticide. It is important to rotate use of pesticides with different modes of action to prevent resistance.  While natural enemies such as the Big-Eyed Bug (pictured below) do exist, they are usually not abundant enough to provide a satisfactory level of suppression.

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For more information on chinchbug management in St. Augustinegrass lawns, please see the UF/IFAS publication at the link below:

http://ufdc.ufl.edu/IR00004254/00001

2 Comments on “Chinch Bugs in Florida Lawns

  1. What is the season for chinch bugs on siesta key florida this year? Are they doing their thing yet? Or do temperatures have to be warmer than now in March 2017? Do cooler nights, as we have been experiencing (sub 60 degrees), keep them under control? Does too much watering help or hurt infestation?

    • Ton:

      Our horticulture team notes that, in our area, chinch bugs are active March through November. But, damage begins in May or June, when the weather turns hot and dry. Turf grass damage tends to first appear in the sunniest, driest areas of the lawn, such as along the edge of a street or driveway or in an open, south-facing area. Chinch bug damage does not occur in cool weather, nor does it generally occur in shade, regardless of the temperature.

      Although chinch bugs tend to avoid wet areas, overwatering will seriously damage or kill your lawn. Never apply extra irrigation in an attempt to control chinch bugs.

      Chinch bugs have developed resistance to many insecticides and satisfactory control requires careful attention. More information about chinch bug management is available at the UF/IFAS Extension publication at the following link: http://manatee.ifas.ufl.edu/comm-hort/pdf/turf/chinchbugmanagementonStAugustinegrass2007LH03600.pdf

      Hope that helps,
      UF/IFAS Extension Sarasota County

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