Destroyed tip of corn, possibly with caterpillar

What’s up with the caterpillars in fresh corn?

I am tempted to make a joke about those songs that you just can’t get out of your head, but instead I’ll just say this: an earworm in your corn is *probably* worse than having Baby Shark on repeat in your head all day. 

Earworms typically only attack the top end of the corn, working their way down until they’ve had their fill and then drop into the soil where they pupate and later emerge as moths. Often, however, their voracious scarfing process is rudely interrupted by the harvest, in which case they may still be munching when you bring your corn home. If you’re seeing a substance that looks like wet, brown dryer lint around the tip of your corn, that’s “frass,” a polite term for what’s basically insect excrement.  If you’re extra “lucky” you may even see the hungry, hungry caterpillar itself.

But the good news is that you can just cut off the damaged area and eat the rest of the corn. Do be on the lookout for mold, however; earworm damage creates mold-friendly conditions. Some molds that form on corn can produce nasty toxins. 

Now, here’s the part of this story you hear less often: that caterpillar you find in your corn is a cannibalistic champion. Please keep reading because, you guys, these little critters are kind of terrible and kind of fascinating. 

How earworms get into corn

Depending on where in the country you are, these creatures, in life stages from egg to larva to moth, may be in the environment year round or they may fly in from down south, possibly riding storm fronts with their bright green eyes fixated on corn crop destruction. These moths can travel 300 miles in a day. 

Mama moths lay batches of eggs on the silky tufts atop corn ears. After hatching, the larvae, which come in a variety of colors, will eat or travel down the silks in a kind of reverse rope climb, until they get to the kernels (silks are pollination tubes for individual kernels!). But note that here I’m writing about eggs plural. Moths lay multiple eggs on each ear of corn. Yet, odds are good you’ll only ever find one caterpillar at a time in your corn. 

Here’s where the cannibalism comes in. The larvae will eat each other until only one remains. So maybe you’ll see the winner doing a little victory dance with its five pairs of prolegs, or little fleshy suggestions of limbs along their abdomen segments.  

How to avoid corn earworms

As a shopper, you can peel off the husk to inspect fresh corn before you buy it. That’s a fine approach, but I don’t do this myself because my favorite way to prepare corn is by microwaving it within the husk, which helps steam it. So, I don’t want to open it up. If I encounter an earworm or earworm damage post microwave, I just cut off that part of the corn. If it’s moldy, I compost the whole thing, which may be overdoing it, but eh. Mold in corn can produce some nasty things. 

A farmer’s or gardener’s battle against the cannibalistic caterpillars depends on geography, resources, and timing. In warmer U.S. regions, earworms overwinter in the soil, so they never really go away. But in cooler areas, farmers may not have serious earworm challenges until later in the season, when the moths fly in from the south.

Since the worms rely on being able to cruise down the silks into the kernels, farmers can also try to cut them off at the pass. That can include using corn varieties with tighter husks, physically pinning the husks shut or applying mineral or vegetable oil on the silks; it will trap the caterpillars.

Farmers can also use pesticides to block the earworm, but this is tricky as the pesticide has to be applied at the right moment, before the caterpillar is in the ear. Once it’s in the ear, you’ve lost the battle. 

What other crops do earworms affect?

If you were to survey earworms, they’d probably tell you that corn is their absolute favorite to eat. But, they’ll diversify their plates as needed. You might also find them on tomatoes, where they’ll leave a black hole near the stem, and frass-filled cavities or on soybeans where they’ll eat away the pod wall and then devour the beans inside. Their different targets, which also include cabbage, peppers, beans, sorghum, cotton, and peanut, have led to their many names: tomato fruitworm, cotton bollworm, podworm. To keep everything straight, their scientific name is Helicoverpa zea.

Do other worms/caterpillars eat corn?

Yes! You might also find a fall armyworm, which comes in light green to brownish shades and features white stripes down its back; or the European corn borer, which is a cream to grayish color. Both are also caterpillars on a mission to eat as much as they can so they can pupate into moths. The fall armyworm and European corn borer are more likely to be in the middle of the corn, rather than the tip. 

This is likely a European corn borer.