Holes in hosta leaves: causes and fixes

The most common cause of holes in hosta leaves in the eastern United States is slugs, followed by deer browse (especially in suburban areas), with earwigs and cutworms as less frequent contributors. The hole pattern, timing, and location of damage are the best diagnostic clues. I

Hostas are among the most commonly damaged shade garden plants, and holes in the leaves are the most common symptom. The challenge: four different culprits produce holes, and each has a different solution. Applying slug bait when deer are the problem, or deer repellent when slugs are eating, wastes time and money.

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Quick diagnostic table

Cause 1: Slugs (most common)

Slugs (Deroceras, Arion, and Lehmannia species) are the number one hosta pest in most of the eastern US. Per Penn State Extension, "slugs are one of the most damaging pests of hostas" and cause "irregular holes with smooth edges" anywhere on the leaf blade, not just the margins.

Confirming slugs: Go out at night with a flashlight, 1–2 hours after dark. If slugs are the culprit, you will see them on the leaves. Per Penn State Extension, slugs "feed at night and on cloudy days." The secondary confirmation is slime trails — silvery dried trails on the leaves or on the soil surface in the morning.

High-risk conditions: Per UC IPM, slugs "prefer cool, moist conditions" and "are most damaging in spring when plants are emerging." In my zone 7a Long Island beds, the worst slug damage happens in April–June during rainy stretches. The sandy loam I garden in dries out faster than clay, which reduces but doesn't eliminate slug pressure.

How to fix:

1. Iron phosphate bait (Sluggo (iron phosphate slug bait), Escar-Go): Per UC IPM, iron phosphate baits are "effective and safe for use around pets, wildlife, and vegetables." Apply granules around hosta clumps after rain or irrigation when conditions are favorable for slug activity. Iron phosphate breaks down into iron and phosphate, which are plant nutrients. Per Penn State Extension, iron phosphate is "the recommended bait for vegetable gardens and areas where pets and wildlife may be present."

1. Reduce mulch depth: Thick organic mulch creates ideal slug habitat. Per Penn State Extension, "keeping mulch to 2 inches or less" around hostas reduces slug shelter.

1. Diatomaceous earth: Sprinkled around hosta crowns, it deters slugs physically. Effective only when dry — rain or irrigation resets it.

1. Copper tape: Copper gives slugs a mild electrical shock. Per UC IPM, "copper barriers can protect individual plants" but require maintenance and reapplication.

See our full guide on slugs and snails for a complete management program.

Cause 2: Deer

In zones 5–8 suburban and semi-rural areas, deer are a major cause of hosta damage. Despite some sources listing hostas as "deer resistant," they are emphatically not — deer browse them readily when other food is limited or when the deer population is high. Per Rutgers NJAES, hostas are rated "frequently severely damaged" in their deer resistance guide.

How deer damage differs from slug damage:

• Deer browse removes large portions of leaves — entire margins or whole leaves stripped back
• Stems may be bitten off at soil level
• Damage is heavier in late summer and fall when natural food sources decline
• No slime trails
• Damage occurs at night in most cases, though deer browse in daylight too

In my zone 7a Long Island beds, deer pressure is significant. My hosta beds are closest to the house and the most accessible when deer visit — they take significant damage in late summer and early fall when dry conditions reduce their food options.

How to fix:

• Physical fencing: The most reliable method. A 6-foot fence effectively excludes deer. Per Penn State Extension, "an 8-foot fence is recommended in areas of very high deer pressure."
• Repellents: Per Penn State Extension, "repellents are effective but must be reapplied after rain and as new growth emerges." Repellents containing putrescent egg solids (Deer Out, Bobbex) are consistently rated more effective than those based on predator urine per field trials.
• Scent deterrents (soap, human hair): Limited effectiveness per Penn State Extension — deer habituate to them quickly.

See our guide on deer-resistant perennials for alternative planting strategies.

Cause 3: Earwigs

Earwigs (Forficula auricularia) chew round to irregular holes in hosta leaves, primarily at night. Per Oregon State Extension, earwigs are "occasional pests of hostas and other shade plants."

How to confirm earwigs: Check under debris, mulch, and leaf litter near the damaged plants in late evening — earwigs hide during the day. Per Oregon State Extension, "earwigs hide in dark, moist locations during the day and feed at night."

How to fix:

• Remove dense mulch and debris that provides daytime hiding spots
• Trap earwigs using rolled newspaper or corrugated cardboard laid on the soil — collect and dispose of in the morning
• Diatomaceous earth around the hosta crown as a physical barrier
• Pyrethrin sprays applied at night when earwigs are active, per Oregon State Extension

Cause 4: Cutworms

Cutworms are soil-dwelling larvae of several moth species. Per NC State Extension, "cutworms damage young plants by cutting through stems at or just below soil level." While they more commonly attack vegetable seedlings, they occasionally damage hostas, particularly young transplants or hostas emerging in spring.

How to confirm: Find a cutworm by digging in the soil 1–3 inches deep near the damaged plant; the larvae are C-shaped, 1–2 inches long, gray or brown. Damage typically occurs in early spring when new growth is emerging.

How to fix:

• Bt (Bacillus thuringiensis (BT spray)) applied to soil as a spray targets cutworm larvae — per NC State Extension, "Bt must be applied when larvae are young and actively feeding."
• Physical collars around young transplants (toilet paper tubes pushed 1 inch into the soil) prevent cutworm access.

Additional causes: hail, herbicide drift, and water quality

Not all hosta holes come from insects or deer. Hail creates circular, clean-edged holes throughout the leaf blade during a storm. Herbicide drift (particularly broadleaf herbicides applied to lawns near hosta beds) can cause irregular holes, browning, and leaf distortion. Per Penn State Extension, "check surrounding areas for herbicide applications" when damage appears suddenly across multiple plants.

Prevention strategies

Site selection: Hostas in partially shaded, well-drained locations have better slug resistance than those in dense, perpetually moist spots. Per Penn State Extension, "good drainage reduces slug habitat."

Cultural practices: Clear away dead leaves and debris from hosta crowns in fall — this removes overwintering slug egg masses. Per UC IPM, "cultural practices that reduce shelter and moisture are the foundation of slug management."

Resistant varieties: While no hosta is truly resistant to determined slugs or deer, thick-leaved varieties are damaged less than thin-leaved ones. Per the American Hosta Society, "hosta varieties with thick, puckered, blue-green leaves (such as 'Halcyon', 'Krossa Regal', and 'Elegans') are somewhat less susceptible to slug feeding than thin-leaved green varieties."

Frequently asked

How do I tell slug holes from earwig holes?

Slug holes tend to be irregular in shape, often along the center of the leaf, and accompanied by slime trails on close inspection. Earwig holes are rounder and more cleanly cut. The most reliable test is nighttime inspection with a flashlight — slugs will be visible; earwigs hide more effectively but can also be found.

Do copper rings around hostas work?

Per UC IPM, "copper barriers can provide some protection" but are impractical for established landscape hostas because the copper ring needs to encircle the entire crown without gaps. They work better for individual pots than for ground-planted hostas. Iron phosphate bait applied around the perimeter is more practical for landscape plantings.

Is it worth replanting hostas that deer keep eating?

If deer pressure is consistently high, replanting the same species repeatedly while doing nothing about deer access is a losing strategy. The practical options are: fence, systematic repellent program (committed to reapplication), or plant deer-resistant alternatives (astilbe, ferns, bleeding heart, pulmonaria, epimedium) in high-pressure areas.

When should I apply iron phosphate slug bait?

Apply when conditions favor slug activity: after rain or irrigation, when temperatures are above 40°F. Per Penn State Extension, slugs "become active above 40°F and are most active at temperatures of 50–65°F." Apply in the evening so the bait is fresh when slugs emerge. Don't apply before hot, dry weather that kills slugs anyway.

Sources

1. Penn State Extension — Slug Management
2. UC IPM — Slugs and Snails
3. NC State Extension — Cutworms
4. Oregon State Extension — Earwigs
5. Rutgers NJAES — Landscape Plants Rated by Deer Resistance