What they are, what they’re doing to your corn fields, and how to stop them
The plague has returned. Japanese Beetles have welcomed themselves back into our corn and given us all that familiar feeling of disgust when walking through our fields. It’s the same story we find ourselves telling in recent years: “They’re in the garden, crawling on the windows, and coming out of the gutters. You can’t take a step without crushing one of these things.”
While these little pests are everywhere, as a farmer you must be concerned about what they are doing to your bottom line. What are they? What do they do to my corn? How do I stop them? These are all questions we will be addressing in this article.
What are Japanese Beetles?
Japanese Beetles are plant-feeders that have taken the United States by storm, but they are not native to the U.S. As the name would suggest, ground zero for this native species is Japan and were not found in the United States until they started turning up in New Jersey in 1916. [1] These beetles from the East are not much of a pest in Japan since they are a prey animal; however they have no natural predators in the U.S. They are a true invasive species, and without predators they have been able to spawn in crazy numbers and shake their new ecosystem. They have spread across the Midwest like a wildfire.
What do Japanese Beetles do to my corn?
Japanese Beetles are the most prevalent in July and August, meaning they hit right during the typical pollination stage for corn and beans (we will talk about beetle damage to beans in a different post). Japanese beetles will feed on corn leaves to a degree, but that usually has little (if any) impact on corn yield. Where these pests really do their damage is the corn silks. Corn silks are an essential part of the pollination process and must be protected. If these little buggers munch through your silks before or during pollination, you can expect your yield to suffer significantly.
How to stop it
Various nets and other capturing tools have been used, but they fill up very quickly and take a lot of maintenance and cleaning out. Even then, it is unclear whether you have made a significant dent in the population on your field, and more and more beetles will move in eventually. Basically, your only real solution to this nasty problem is to spray your field with an insecticide, which is generally done with either a plane or helicopter.
Now timing is important, as these six-legged varmints are persistent and unwilling to be gone for a long period of time. Given the labeling laws, only certain insecticides may be used on corn, none of which have any significant residual effect (meaning the chemical doesn’t stay in the plant for long periods of time). Some beetles will die, but most will just disperse from your field and return when it is safe again. Your best bet is to hit them with insecticide right at pollination before they start feeding on the silks. That should knock them out of the field long enough for the pollination process to finish and for your corn to reach brown silk. From there, the silks have done their part and the beetles feeding on them will have little or no effect on yield.
Conclusion
We know how incredibly annoying Japanese Beetles are and how much damage they can really do, but you can overcome this plague. These bugs of burden can be managed, but in the end, you must manage them and manage them wisely using proper methods and timing.
Service and Supply Cooperative has several experts on staff that can help guide you towards making the right decision whether insecticide is right for you and your fields. We also have the insecticides you need to make a real difference when and where it counts with these problem pests, as well as access to aerial application services to get your products on when you need it.
If you’re ready to take a serious step towards protecting your plants from this onslaught of beetles, then you can call or visit any of our locations to get on the list for spraying here, or if you would prefer to email us then you can click here.
Also, if you are considering spraying your fields for insects, you may consider using fungicide as well. For a slight up-charge, you can be protected from both diseases and insects this year. To learn more about adding a fungicide, you can read our article on that very subject here.
Thank you and good luck!
[1] USDA. “Managing the Japanese Beetle: A Homeowner’s Handbook.” United States Department of Agriculture , Aug. 2015, www.aphis.usda.gov/plant_health/plant_pest_info/jb/downloads/JBhandbook.pdf.
