Grandfather’s Corn Rootworm Beetle Identification and Management Tips

July 30, 2014

Over the past weekend, I had some one on one time with my grandfather. We had the chance on Sunday afternoon to take a look at some corn on his farm in northern Indiana. The hybrid on this particular field happened to be a conventional hybrid. A few rows in, I noticed two corn rootworm beetles on the tip of the ear, feeding on the silks. The little black and yellow beetles were scurrying around chewing and clipping the silks as fast as possible.

“Tell me about those little critters” Grandpa said. As a school teacher for 31 years, I knew he was asking this question for a chance to share some additional information.  I said “Well, they are adult corn rootworm beetles. We’ll need to keep an eye on these populations especially during pollination because they can harm the receptiveness of these silks and can damage yield due to poor kernel fill.”

Figure 1: Western, Northern, and Southern Corn Rootworm Beetles

Figure 1: Western, Northern, and Southern Corn Rootworm Beetles

“That’s right, and let me tell you how to identify the different species. Northern corn rootworm beetles have a green tint to them. Western corn rootworms will be yellow and black with the females having a sequence of 3 black lines down their back. These three lines look similar to the letter “W” which stands for western. These have been the most common on my farm. Southern rootworm beetles are yellow and black as well but have a spotted pattern on their backs. They don’t have much of an effect this far north because their eggs do not over winter.”

Here are a few hyperlinks for more information on Corn Rootworm management:
http://extension.entm.purdue.edu/fieldcropsipm/insects/corn-rootworms.php
https://ipm.illinois.edu/fieldcrops/insects/corn_rootworm/factsheet.html

-Scott Sanders, Seed Specialist