How to Manage Pests
UC Pest Management Guidelines
Southern Chinch Bug
Scientific Name: Blissus insularis
(Reviewed 9/09, updated 9/09, pesticides updated 12/16)
In this Guideline:
DESCRIPTION OF THE PEST
Southern chinch bug adults are black with whitish wings that fold flat over their body. They are about 0.125 inch(0.3 cm) long. Both long- and short-winged adult forms may be present. Early instar nymphs are bright red but darken to black by the last instar. There are several generations a year, with all life stages present during summer; populations tend to be highest when temperatures are above 90°F. All life stages usually reside in the turfgrass crown and the thatch, but can also be observed at the border between damaged and healthy grass. Big-eyed bugs, which are beneficial predators, are similar in appearance to chinch bugs but their large eyes, which are the widest part of their body, distinguish them from chinch bugs.
Although bermudagrass, buffalograss, and zoysiagrass are fed upon, only St. Augustinegrass is seriously damaged in California.
Chinch bugs are active from April through October, especially in full sun. Southern chinch bugs suck sap from nodes and crown of the turfgrass. Yellowish to brownish patches result.
When southern chinch bug occurs in turfgrass, decrease fertilizer rates and maintain adequate moisture. Usually only St. Augustinegrass is significantly damaged by this pest. Treatment may be required if monitoring indicates a need.
Big-eyed bugs, ants, and the fungal insect pathogen Beauveria bassiana are the most important natural enemies of chinch bugs. Maintaining moist conditions favors development of Beauveria.
If St. Augustinegrass is desirable, select resistant varieties such as Floralawn, Floratam, or FX-10. Thatch removal is important for eliminating conditions favorable for chinch bug survival. Applying the low end of recommended nitrogen slows chinch bug reproduction. Maintaining adequate moisture will increase the tolerance to chinch bug feeding and promotes beneficial fungi that attach chinch bugs.
Monitoring and Treatment Decisions
Use the flotation method or drench test to determine chinch bug presence and population level. For the flotation method, take a 6-inch diameter coffee can, remove top and bottom, and set it 2 to 3 inches into the turfgrass. Fill it with water and wait for 5 to 10 minutes for bugs to float to the surface. The drench test is described in the section MONITORING AND TREATING INSECTS AND MITES. Treat when combined nymph and adult counts average at least 3 per coffee can sample, or 135 per square yard. Mow the lawn and irrigate before treating. After treatment, do not mow or irrigate for at least 24 hours.
UC IPM Pest Management Guidelines: Turfgrass
Insects and Mites
A. M. Sutherland, UC Statewide IPM Program, Alameda County
Acknowledgment for contributions to Insect and Mites:H. K. Kaya, Nematology, UC Davis
J. Hartin, UC Cooperative Extension, San Bernardino County
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
K. Kido, Entomology, UC Riverside
H. S. Costa, Entomology, UC Riverside
D. D. Giraud, UC Cooperative Extension, Humboldt/Del Norte counties