Holes in tomato leaves: causes and what to do
Small, scattered holes in tomato leaves are almost always flea beetles. Large, ragged holes or missing leaf sections are usually tomato hornworm caterpillars. The good news: tomatoes tolerate substantial leaf damage without yield loss, per most Extension research. The diagnostic
Holes in tomato leaves are a common mid-season sighting, and the size and pattern of the holes narrow down the cause quickly. Some are urgent; most aren't.
This article contains affiliate links. As an Amazon Associate, we earn from qualifying purchases - at no extra cost to you. We only recommend products we have personally tested or that are the universal first recommendation from university Extension publications. See our full disclosure.
Cause 1: Flea beetles (most common, usually minor)
Flea beetles (Epitrix spp.) are tiny, jumping beetles that create small, round to irregular holes, 1/16 to 1/8 inch in diameter, across the entire leaf surface. Per Penn State Extension, "flea beetles create a characteristic 'shot-hole' damage pattern — many small holes scattered across leaves."
How to identify: The beetles are very small (1/16 inch), dark, and jump like fleas when disturbed. They feed during the day.
When it matters: Per Penn State Extension, "flea beetle damage to established tomato plants is typically cosmetic and does not warrant treatment." The seedling and transplant stage is when flea beetles are most damaging — small plants with heavily shot-holed leaves can be set back.
How to manage:
- For transplants, floating row cover until plants establish provides effective protection
- Kaolin clay sprayed on foliage repels flea beetles by physical deterrence
- Spinosad is effective for heavy infestations on small plants per Penn State Extension
- For established plants producing fruit, no treatment is typically needed
Cause 2: Tomato hornworm
The tomato hornworm (Manduca quinquemaculata) is one of the largest caterpillars in North American gardens — up to 4 inches long, bright green with diagonal white stripes and a red-orange horn at the rear. It can consume entire leaves and even stems rapidly.
How to identify: Per Penn State Extension, "hornworm feeding creates large, ragged holes or complete defoliation of stems." Hornworms are very well camouflaged against tomato foliage — look for their black droppings (frass) on leaves below the feeding area, which reveals the caterpillar is higher on the plant.
When it matters: A large hornworm can consume a significant amount of foliage in a day or two. Multiple hornworms on a single plant can cause serious defoliation. Per Penn State Extension, "one or two hornworms on a large plant typically cause acceptable damage; five or more warrant treatment."
How to manage:
- Hand-pick: The most effective method for small numbers. Drop in soapy water.
- **Bt (Bacillus thuringiensis (BT spray)):** Per Penn State Extension, "Bt is the most effective and selective treatment for hornworms." It targets caterpillar larvae specifically, with no effect on bees, beneficial insects, or other non-targets. Apply to the foliage where caterpillars are feeding; they must ingest Bt to be affected.
- Parasitized hornworms: If you see hornworms covered with small white cocoons (braconid wasp egg cases), do not remove them. Per Penn State Extension, "the wasp parasites will eventually kill the hornworm and go on to parasitize others." These parasitized hornworms are doing you a favor.
See our full article on tomato hornworm for complete identification and management.
Cause 3: Other caterpillars
Several other caterpillar species occasionally feed on tomato foliage, including variegated cutworm (Peridroma saucia), tobacco budworm, and cabbage looper. Per Penn State Extension, "Bt applications effective against tomato hornworm will also control these caterpillars."
Cause 4: Slugs
In cool, moist conditions — particularly early in the season — slugs feed on tomato foliage at night. Damage appears as irregular holes often near the base or on lower leaves, with slime trails visible in morning.
How to manage: iron phosphate slug bait. Reduce mulch around plant bases to eliminate slug habitat.
Cause 5: Hail
Hailstorms produce round to irregular holes with clean edges throughout the plant canopy. Unlike insect feeding, hail damage appears suddenly after a storm, affects all plants uniformly, and may also show bruising or discoloration at wound edges.
What to do: Nothing. Per Penn State Extension, "tomatoes typically recover from hail damage if the plants are otherwise healthy." Avoid spraying copper or other chemicals immediately after hail damage — open wounds are more vulnerable to uptake. Let wounds callus for 2–3 days before any spray applications.
The yield tolerance question
Per NC State Extension, "tomato plants can tolerate loss of up to 30% of foliage without significant yield reduction." This means that a plant with some flea beetle holes or hornworm feeding that still has most of its leaves is not going to produce significantly less fruit because of that damage.
The practical implication: before treating, assess whether the damage is cosmetic or whether it's actually removing enough leaf area to reduce yield. An established, large tomato plant with 100+ leaves can lose 30 of them without you noticing the effect on harvest.
Common mistakes
| Mistake | What happens | Fix |
|---|---|---|
| Treating flea beetle holes on large plants | Unnecessary; doesn't improve yield | Assess the damage level; skip treatment on established plants |
| Removing parasitized hornworms | Kills the beneficial wasps | Leave hornworms with white cocoons; they are effectively dead |
| Using broad-spectrum insecticides for hornworms | Kills beneficial insects; disrupts natural hornworm control | Use Bt instead — selective and effective |
| Not checking for frass before searching for hornworms | Wasted search time | Find black frass, look directly above on stems |
Frequently asked
How do I find hornworms if I can't see them?
Per Penn State Extension, "look for black droppings (frass) on leaves below where the caterpillar is feeding." The frass looks like small dark pellets; follow the frass upward on the stem and you will find the caterpillar above. Check during the day in direct sun — hornworms glow slightly under UV light, which can help.
Should I spray insecticides on all my tomatoes as a preventive measure?
No. Per Penn State Extension, "preventive insecticide applications on tomatoes are not recommended in home gardens." Spray only when pest populations and damage levels justify treatment. Unnecessary insecticide use disrupts beneficial insect populations (parasitic wasps, predatory beetles) that help control tomato pests naturally.
Are tomato plants safe to eat when they have holes in the leaves?
Yes. Leaf damage from insects does not affect fruit safety or quality.
Sources
- Penn State Extension — Flea Beetles and Hornworm Management
- NC State Extension — Tomato Foliar Pests
- UC IPM — Tomato Pest Management
Sources
- 1. Penn State Extension — Flea Beetles and Hornworm Management
- 2. NC State Extension — Tomato Foliar Pests
- 3. UC IPM — Tomato Pest Management