Examine the scene of the crime
Each chewer has its own way of damaging plants. Careful examination of the damage makes it easy to distinguish between the various types of chewers, and then form a plan to curtail their devilish deeds. Japanese beetles chew jagged holes in both leaves and flowers, sometimes skeletonizing their victims and leaving only the tough leaf veins intact. These garden gourmands will chomp on over 300 different types of plants, but have a weakness for rose petals and blossoms. And damage from Japanese beetles doesn’t end with the arrival of cooler weather. Their larvae destroy lawns by burrowing into the ground and feeding on grass roots during the fall into the spring.
Caterpillars are masters of disguise. Their mottled green to brown color helps them blend into their surroundings, and their common position on the undersides of leaves and leaf stems makes them difficult to spot. Caterpillars create smooth-edged holes of various sizes on a long list of trees, shrubs, and herbaceous plants. Another sign of caterpillars is the little pellets they leave behind on the chewed leaves. These voracious chewers are active day and night, but less so in cold, rainy weather.
Slugs and snails usually shear off the edges of plants and may eat through the leaves, stems, and buds until entire plants are consumed. They almost always work at night, or on cool, overcast days. Like most classic villains, they leave an unmistakable clue behind—a glistening trail of slime. Low-growing, herbaceous plants like hostas and the tender, emerging shoots of spring bulbs are especially irresistible to slugs and snails.