If you enjoy a dense green St. Augustinegrass lawn, then you absolutely hate chinch bugs. They are the biggest pest of St. Augstinegrass lawns! Chinch bugs are very small insects that live in your turf that have a straw for a mouth, and they get drunk on your grass. The chinch bug inserts the straw into your grass and sucks the life giving green goodness right out of the grass blades. They like to hide in between the sheaths of the leaf blades, and in the thatch layer in the turf. Chinch bugs can happen anytime, but are most problematic during the warm season in areas that have been stressed.
Turf can get stressed from a few main things that are pretty simple to control by using best management practices.
- Poor irrigation distribution
- Mowing too short
- Too much nitrogen in the fertilizer
Even the best practices can still result in some pest issues, so the next best thing to do is scout! Scout for the chinch bugs and properly ID the cause of the issue so that you can select the best treatment. I know you are tempted to just treat, treat, treat, to keep these critters controlled, but unfortunately chinch bugs are becoming resistant to the best insecticides in our pesticide cabinet.
- Monitor your landscape for potential pest issues. Chinch bugs live in groups, and their damage is characterized by an irregular pattern spreading outwards.
- Suspect chinch bugs? Get a handheld vacuum and vacuum about 1 square foot of grass in an area with half and half dead and living grass. This is likely a zone of active feeding.
- Dump debris from vacuum onto a white paper or light colored tray and count the chinch bugs. If you have 20 or more chinch bugs, treat that chinch!
A few important notes. You need to know what you are looking at, so proper insect ID is paramount. Insects go through stages of metamorphosis, so you need to be familiar with what a chinch bug looks like at each stage of growth including egg, nymph, and adult stages. There are some insects in the turf that are considered good guys. The big-eyed bugs could be easily confused with a chinch bug, except “big-eye” is beneficial and eats chinch bugs for breakfast! Thatch management is also important so that organic matter is regularly decomposing as opposed to building up beneath the turf. If you circle back to proper irrigation, mowing height, and proper fertilization, thatch should not be a major issue.
The final note on management is to ROTATE MODES OF ACTION! Chinch bugs are a major pest of a major crop. Systemic pesticides have certain advantages when managing chinch bugs and must be employed strategically in a plan that does rotate through multiple groups to avoid resistance. UF/IFAS Extension lists different chemicals and modes of action to assist with your proper planning and successful implementation of Integrated Pest Management.
More detailed information here: https://edis.ifas.ufl.edu/lh036
Heading photo courtesy of NC State Extension: https://content.ces.ncsu.edu/chinch-bug-in-turf