In Too Afraid to Ask, we’re answering food-related questions that may or may not give you goosebumps. Today: There’s a sneaky caterpillar eating the corn you just bought—what now?
Maybe you’ve been here before: You’re at the farmers market piling sweet corn into your tote bag, unaware of what you’ve just unwittingly invited into your kitchen. Back home, you unwrap those ears to toss them on the grill and—gasp—find a fleshy caterpillar, with tiny hairs sprouting from its striped back, actively mauling the kernels.
They might look small and meek, but don’t underestimate the corn earworm: When two encounter each other while munching on a juicy cob, they’ll stop what they’re doing and fight to the death. They put their squishy, two-inch bodies on the line: “A battle ensues, resulting in one survivor and one meal,” says David T. Handley, PhD, a vegetable and small fruit specialist at the University of Maine. “They’re cannibalistic.” This aggressive tête-à-tête, which happens in secret beneath corn’s pale green husks, is why you’ll often find just one single critter feasting on your cob.
Come picnic season, when you’re amped to make a corn salad, zesty elote, or cheesy casserole before taking an afternoon nap in the hammock, it can be jarring to find a little dude has been making himself at home on your food. So, who are these worms? And what should you do if you come across one chowing down on your fresh corn this summer? Before firing up the grill, here’s what to know.
Who is that worm in your corn?
There are plenty of pests that attack corn crops grown in the US, but the one you’re most likely to find this summer is the corn earworm—which is technically a caterpillar. Brown, tan, green, or pink with bumpy bodies and longitudinal stripes, these caterpillars are the larvae of moths, which lay tiny eggs (“smaller than the head of a pin”) directly on corn silks, says Marissa Schuh, a horticulture and integrated pest management educator at the University of Minnesota.
If they’re not managed in time, those eggs hatch and tiny caterpillars haul themselves under the husks using the silks, like rock climbers working their way up a rope. At that point, “farmers can’t really do anything about them,” says Schuh. Because all the action happens under cover, and there’s no visible damage to the silk or husks, corn earworms often make it past quality checks and into your shopping cart.
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Why are only some corncobs affected?
Corn earworm eggs usually don’t discriminate between varieties of corn, but there are a few factors that could explain why these pests can be more of an issue for some farmers.
Firstly, geography. The moths that lay corn earworm eggs have “a constant presence in Southern states,” says Shuh. Whereas, in the Northern US, their seasonal prevalence is driven by weather patterns, such as storm fronts, that carry moths into those areas—and most don’t survive the winter. Temperature also plays a role. Moths are more active in very hot conditions, says Handley, and these factors also mean pesticides tend to break down quickly, making it harder to stop infestations.
