Corn Earworms: How To Get Rid Of The Destructive Pest That's Ruining Your Crops

A sweet ear of corn with the right amount of crunch makes growing pains worth it. But corn earworms might be the pest to break your spirit and make you rethink growing corn in your backyard. These pests weasel their way into young ears of corn and eat up the kernels, making a good portion of each ear inedible. Fortunately, you don't have to turn to harmful chemicals to get rid of these awful pests. You can eliminate them with just a bit of mineral oil and a dropper.

Mineral oil is found in many cosmetic and drug products and is usually sold as baby oil, though some baby oils may have other ingredients added to them. You should be able to buy some at your grocery store or drug store on the lotion aisle. It's a natural product derived from petroleum, and it's safe to use on your plants. It's a highly effective solution against corn earworms, so while you may want mineral oil on hand for cosmetic purposes, it will also serve you well in the garden.

Use mineral oil to get rid of corn earworms

A pamphlet from the USDA National Agricultural Library dating back to 1943 explains to those growing victory gardens how to use mineral oil on corn to fight off earworms, so this isn't just some nifty viral hack — it's a tried and true method! All you need is pure mineral oil and a dropper. Add about five drops to the silk of each ear of corn, and you'll have dead earworms in no time. They suffocate in the oil and die before they can harm your corn, leaving you with spotless corn cobs.

There are other ways you can approach this method if you don't have mineral oil or just prefer something else. A study in the Journal of Economic Entomology tested various oils against earworms, including canola, olive, and peanut, among others. They were all effective to some degree in the two-year experiment, so you can use whichever of these oils you already have in your pantry. If you want to be even more thorough, add some Bacillus thuringiensis, or Bt, to the oil. Bt is a type of bacteria that can kill insects. According to North Dakota State University, use 20 parts oil and 1 part Bt. Mix it up and then apply five drops to the corn. If the oil doesn't kill the earworms, the Bt will.

Get the timing just right

The timing of your mineral oil application will make or break you. The best time to take action is when the silks first start to turn brown. This is about when the earworms are getting ready to burrow into the husks. If you apply before the silks start wilting, the earworms will just be eggs and it won't be as effective. Plus, it could interrupt the corn's pollination process. If you wait until all the silk is brown, it will be too late, as the earworms will have already started feasting on your crops.

It helps to understand the lifecycle of earworms so you can properly fight against them. The earworms on silks are the second generation. The first generation lived its life in the crevices where the leaves meet the stalks while your corn was at your knees or shorter. They hid themselves while they turned into pupae to turn into moths. Those moths laid eggs on new corn silk, and those are the ones gobbling up your corn. They eventually dig their way out of the corn husks and drop to the ground, where they mature into moths. Understanding their lifecycle gives you a chance to get ahead of their control. You can look for eggs or holes in the husks to monitor if it's too early or late to apply mineral oil.