Home and Landscape

Sunflower Beetle

  • Zygogramma exclamationis
Updated: 04/2026

Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.

Information in this database comes from published articles. It may be used in conjunction with field monitoring and a degree-day calculator.

Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.

Model 1

Charlet, L. D. 1991. Overwintering survival and emergence pattern for the sunflower beetle (Coleoptera: Chrysomelidae) in the northern great plains. J. Econ. Entomol. 84: 132-135.

  • Location of study: Fargo, North Dakota (field studies)
  • Lower developmental threshold: 32F (0°C)
  • Upper developmental threshold: 90F (32°C)
  • Method of calculation: Single Sine
  • Cutoff method: not specified (UC IPM recommends Horizontal)

Degree-day accumulations required for each stage of development

Start date: March 1

Host: Sunflower

  • First dault emergence: 418 (°F) 232 (°C)
  • 50% adult emergence: 711 (°F) 395 (°C)