Leaf Holes

Leaf holes may indicate insect feeding, disease, or chemical or physical damage. 

Leaf holes interfere with photosynthesis, which weakens the plant, and it becomes more vulnerable to other pests and diseases. Use the information below to learn how to identify the cause of leaf holes in your garden or landscape plants. Once you know the reason, you can select the best treatment.

Snail feeding damage on salvia

Physical damage

Many citrus leaves exhibit holes caused by nearby thorns. Wind-whipped branches can also puncture leaves. In these cases, there is nothing you can do. 

Chemical damage

Chemical damage is usually caused by herbicide overspray, yours or your neighbors'. Using chemical herbicides more carefully (or not at all) can help prevent this.

Irregular holes

Irregularly shaped holes and complete defoliation, with the central leaf vein left intact, are usually caused by these insects:

• Cabbage loopers - one inch or longer green larvae, move inchworm fashion; leave dark green droppings; usually present July and August
• Cabbageworms - one-inch green larvae with pale yellow side stripes; feed during the day and leave brown droppings; present through the growing season
• Hornworms - they can reach 3 to 4 inches in length and will devour small stems and entire leaves on members of the nightshade family (tomatoes, potatoes, eggplant, peppers)
• Slugs and snails feeding at night - they leave a tell-tale slime trail; present year-round

Flea beetle feeding damage

Ragged edges and shot hole appearance

Small, irregular leaf holes that merge to create raggedy areas are a symptom of flea beetle feeding. Flea beetles are only 1/16 to 1/8 of an inch long. They can be black, brown, bronze, bluish, or gray. Flea beetles are present throughout the growing season. If the holes look more similar to a shotgun blast, it is probably shot hole disease.. Shot hole disease holes usually begin as 1/10 to 1/4 inch diameter red or purplish spots. Each spot may have a pale green or yellow ring around it. As the dead tissue dries up and falls away, the leaves look like victims of a shotgun blast.

Irregular holes, chewed stems, chlorosis, and wilting

This recipe for disaster indicates the presence of cucumber beetles. Cucumber beetles can be striped or spotted. And they nearly always cause significant plant damage.

​Opaque windows

Western avocado leafrollers (Amorbia cuneana), orange tortrix (Argyrotaenia citrana), and other leafroller larvae feed on single layers of leaf material, creating opaque windows that eventually dry up and fall out. These larvae are usually green and less than one inch long. Older larvae may start chewing through entire leaves, usually from the outer edge, and working inward. Windows may also indicate fungal diseases and leaf miners.

Spotted cucumber beetle leaf feeding (Melissa McMasters) CC BY 2.0

Leaf miner damage on beet leaf

Oval lesions

Anthracnose fungi can cause circular or angular brown spots on leaves and sunken oval lesions on large leaf veins. The browned areas turn white before falling out. Wilting of outer leaves is another symptom of anthracnose.

​Leaf slits

Anthracnose on tomato leaf (Scot Nelson)

If your grape leaves look as though a tiny, knife-wielding slasher attack occurred, it was probably the Western grape rootworm (Bromius obscurus). Leaf slits are usually 1/4 to 1/2 inches long. Individually, these slits are too small to seem important, but the combined effect can be devastating to individual leaves. Grapes are also damaged.

Fuller rose beetle damage

Scalloped edges

Weevil feeding can result in scalloped edges on lilac, rose, citrus, or avocado leaves. One adult weevil, the Fuller rose beetle, causes cosmetic damage to many different fruit and ornamental trees and shrubs. But the underground larvae are the real problem as they feed on roots. Other weevils, which tend to be long-nosed beetles, can cause damage to plants above and below the soil level.

This list is not exclusive but should give you a good starting point.