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No, you aren’t seeing western corn rootworm adults right now

May 7, 2018
Content Author: Erin Hodgson

Over the weekend, someone let me know they saw a western corn rootworm adult. Remember this pest overwinters as an egg that hatches in June! They get confused with closely-related species every spring: striped cucumber beetle. Striped and spotted cucumber beetles overwinter as adults and become active when spring temperatures warm up. Most scouts are able to distinguish northern corn rootworm and southern corn rootworm (also known as spotted cucumber beetle) fairly easily. However, western corn rootworm and striped cucumber beetles can be distinguished by the stripes on the forewings.

western corn rootworm
Western corn rootworms are yellow with a dark head. Females have three black lines on the forewings that do not extend to the wing tip. The forewings of males often look like a black smudge (note one male in this photo). Photo by Purdue Extension.
striped cucumber beetle
Striped cucumber beetles are yellow with a dark head and have three crisp dark lines on the forewings that extend all the way to the wing tip. Photo by Jim Jasinski, www.ipmimages.org.
spotted cucumber beetle
Spotted cucumber beetle (southern corn rootworm) are yellow with a dark head and have 11 black spots on the forewings. Photo by Jim Jasinski, www.ipmimages.org.
corn rootworms
Left to right: southern corn rootworm (spotted cucumber beetle), western corn rootworm, and northern corn rootworm. Photo by Adam Varenhorst. 

 

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Authored by
Photo of Erin Hodgson
Erin Hodgson
  • Professor
  • Extension Entomologist Specialist
  • ANR Crops Team Leader
Dr. Erin Hodgson started working in the Department of Entomology, now the Department of Plant Pathology, Entomology, and Microbiology, at Iowa State University in 2009. She is a professor with extension and research responsibilities in corn and soybeans. She has a general background in integrated pest management (IPM) for field crops. Dr. Hodgson's current extension and research programs are focused on improving corn and soybean production by using IPM tactics to protect yield and increase overall farmer profits. Among other projects, she oversees insecticide efficacy evaluations for soybean aphids, Japanese beetles, and aphids in corn. Erin also helps manage emerging field crop pests and invasive species.

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