Unveiling the Mystery: The Small, Round Pellets on Your Trees

What Are Those Small Pellets?

The most common explanation is insect frass, which is a polite term for insect droppings. Certain tree-dwelling insects—especially caterpillars, beetles, and borers—produce small, pellet-like waste as they feed on leaves or wood.

These pellets are often:

• Round or oval
• Tan, brown, or dark-colored
• Found beneath branches or clinging to bark

Which Insects Cause Them?

Several insects are known for leaving behind these telltale pellets:

• Caterpillars – Often drop frass from feeding in the canopy, which collects on lower branches or the ground.
• Wood-boring beetles – Push pellets out of small holes in tree bark as they tunnel inside.
• Sawfly larvae – Produce pellet-shaped droppings similar to caterpillars.

Identifying the insect usually depends on where the pellets appear and whether you see leaf damage or tiny holes in the bark.

Are the Pellets Harmful?

The pellets themselves are harmless, but they can signal a larger issue. Heavy frass buildup may indicate a significant insect infestation, which could stress or weaken a tree over time. Signs to watch for include:

• Chewed or missing leaves
• Holes in the trunk or branches
• Sawdust-like material near the bark
• Wilting or thinning foliage

What Should You Do Next?