Corn is a widely cultivated crop, providing sustenance globally. Its tender kernels and robust stalks make it a desirable food source for various organisms, rendering it vulnerable to numerous garden pests throughout its growth stages. This article identifies common culprits, from tiny insects to larger animals, that feed on corn.
Common Insect Pests
Corn earworms are prevalent pests, primarily targeting developing kernels within the ear. They also feed on silks and leaves. Damage to silks can reduce pollination and lead to poorly filled ears. Evidence of their presence includes frass (excrement) and mold growth within the ear, as feeding creates entry points for secondary pests and fungi.
Cutworms damage corn seedlings, often cutting them at or just below the soil surface. This causes plants to wilt, die, or results in reduced plant stands. Smaller larvae might leave irregular holes in leaves, while larger ones can completely sever stalks. Cutworms are active at night or during overcast days.
Fall armyworms consume corn leaves, ears, and tassels, creating ragged holes. Early damage may appear as small holes in leaves emerging from the whorl. Larvae often hide deep within the whorl, protected by frass. They can also feed on developing ears, sometimes burrowing through the husk.
European corn borers tunnel into stalks and ears, disrupting the plant’s ability to transport water and nutrients, stunting growth and causing plants to fall over. Signs of their activity include broken leaf midribs, tassels with sawdust-like frass, and holes in stalks and ears. This internal damage can lead to reduced yield, lodging, and ear drop, and providing entry points for stalk and ear rots.
Aphids feed by sucking sap from corn leaves and stalks. Heavy infestations can cause leaves to wilt, curl, and yellow discoloration. These pests excrete a sticky substance called “honeydew,” leading to sooty mold growth on plant surfaces, interfering with photosynthesis. When tassels and silks are covered with honeydew, pollination may be disrupted, resulting in incomplete kernel development or barren ears.
Japanese beetles primarily damage corn silks during pollination, significantly affecting yield if silks are clipped. They also feed on corn leaves, causing a skeletonized or lacy appearance, though this leaf damage is less impactful on yield. These beetles are shiny metallic green with bronze wing covers.
Corn rootworms are damaging in their larval stage, feeding on corn roots. This root injury impairs the plant’s ability to take up water and nutrients, leading to stunted growth, lodging, and reduced yield. Damage to roots can appear as feeding scars, tunneling, or roots completely consumed to the base, creating entry points for soil-borne diseases.
Mammalian Culprits
Deer consume various parts of the corn plant, including leaves, stalks, and ears. Their feeding leaves ragged edges on plants, and they can trample fields, causing additional damage. Deer damage is more concentrated near wooded areas where they seek cover.
Raccoons damage corn primarily during the milk stage, when kernels are soft. They pull down stalks to access ears, peeling back husks to eat the kernels. Raccoon activity leaves a messy appearance, and husks may appear muddy from their handling.
Squirrels gnaw on corn ears. Their damage occurs close to wooded areas and is identified by scattered pieces of corn on the ground. Squirrels and other small mammals may also dig up and feed on planted seeds or young seedlings.
Groundhogs primarily eat young corn plants and leaves. These herbivores consume significant vegetation daily. Groundhogs forage in the early morning and scurry to their burrows when disturbed.
Mice and voles target corn seeds, newly germinated seedlings, and lower kernels on ears. Voles create shallow tunnels beneath the soil surface. They cause significant stand reductions by eating newly planted seeds or nipping off new seedlings.
Feathered Foes
Crows pull up newly sprouted corn seedlings. They also feed on kernels from mature ears, leaving distinctive peck marks. Their activity is visible by disturbed soil around young plants or damaged ears in the field.
Blackbirds, sparrows, and starlings peck at kernels on the ears. Blackbirds eat kernels from ears, particularly during the milk stage when the corn is soft. Sparrows and starlings similarly target the kernels, leaving punctured seeds on the cob.
Bird damage does not involve knocked-over stalks, unlike some mammalian pests. Instead, visual evidence includes plucked seedlings or distinct pecking damage on mature cobs. The presence of these birds in large flocks amplifies the damage.
Protecting Your Harvest
Identifying the specific culprit behind corn damage is a first step toward effective protection. Different pests necessitate varied approaches. General methods for protecting corn involve creating physical barriers, such as fencing or netting, to exclude larger animals and some birds.
Implementing appropriate cultural practices also helps reduce pest pressure. This includes timely planting to avoid peak pest activity or rotating crops to disrupt pest life cycles. Monitoring fields regularly for signs of damage and pest presence allows early intervention. While specific solutions vary by pest, understanding the consumer guides targeted and efficient protective measures.