---
title: Frass: The Dust and Pellets Insects Leave Behind
url: https://battleborntreeservice.com/glossary/frass/
business: Battle Born Tree Service
address: 6301 US Highway 50 East, Carson City, NV 89701
phone: 775.232.8243
hours: Office Monday-Friday 8:30 am-5:00 pm; phones answered seven days a week; 24-hour emergency service
credentials: ISA Certified Arborist WE-11728A on staff; Nevada Business License # 20131580674; fully insured
type: Tree service (removal, crane work, pruning, stump grinding, defensible space, snow removal, firewood)
---

- [Home](https://battleborntreeservice.com/)
- [Arborist glossary](https://battleborntreeservice.com/glossary/)
- Frass

# What is frass?

Frass is the mix of boring dust and droppings that insects leave behind when they feed inside or on a tree. It is one of the first visible signs that something is eating the wood or bark.

## What it looks like and where it shows

Fine, sawdust-like material in bark crevices, at the base of a trunk or on the ground below a hole usually points to wood-boring insects, including bark beetles. In pines it can be mixed with pitch. Fresh frass is light and clean; old frass is weathered and darker. The pattern matters: a few specks on a cut stump is a different thing from a drift on every trunk on the street.

Frass tells you something is present. It does not tell you which insect or whether it is still active, which is why identification comes first. See [bark beetles in pines](https://battleborntreeservice.com/tree-guide/bark-beetles-in-pines/) and [fir engraver beetle](https://battleborntreeservice.com/tree-guide/fir-engraver/).

## Why it matters in Northern Nevada

Pines and firs stressed by drought are the usual targets in our foothills and at Tahoe, and bark beetles often attack stressed trees. Boring dust at the base of a pine, together with needles that fade from the top, can be an early warning. Some decline is not insect-related at all. See [drought stress and dieback](https://battleborntreeservice.com/tree-guide/drought-stress-and-dieback/).

Frass on firewood is another common sighting. Do not move firewood: see [the Nevada rules](https://battleborntreeservice.com/guides/dont-move-firewood-nevada/).

## What an arborist does about it

The arborist traces the frass to its source: the holes, the species of tree, where on the trunk and how far the damage goes. The question is not "what do I spray" but whether the tree is alive and how to handle what is dead: prune a limb, take the tree down, or monitor. Battle Born does not spray or treat trees; our part is identifying the problem and the pruning or removal decision. A dead pine over a house is a removal job. See [removing dead pines after bark beetles](https://battleborntreeservice.com/guides/removing-dead-pines-bark-beetles/).

### Sources

- [International Society of Arboriculture, Trees Are Good: Insect and Disease Problems (brochure)](https://www.treesaregood.org/Portals/0/TreesAreGood_Insect%20Disease%20Problems_0721.pdf) (read October 17, 2026)

### Talk to the office

[775.232.8243](tel:775.232.8243)

| Monday to Friday | 8:30 am - 5:00 pm |
|---|---|
| Saturday and Sunday | Office closed, phones answered |

Phones answered seven days a week. 24-hour emergency service.

[Free estimate](#quote)

### Keep reading

- [Arborist glossary](https://battleborntreeservice.com/glossary/)
- [Bark beetles in pines](https://battleborntreeservice.com/tree-guide/bark-beetles-in-pines/)
- [Fir engraver beetle](https://battleborntreeservice.com/tree-guide/fir-engraver/)
- [Removing dead pines after bark beetles](https://battleborntreeservice.com/guides/removing-dead-pines-bark-beetles/)

## See also

[Cambium](https://battleborntreeservice.com/glossary/cambium/) [Conk](https://battleborntreeservice.com/glossary/conk/) [Cavity](https://battleborntreeservice.com/glossary/cavity/)

## This term in our guides and answers

[What are the rows of small holes in my tree's bark?](https://battleborntreeservice.com/faq/tree-health-and-problems/what-are-the-rows-of-holes-in-my-tree-bark/) [Removing dead pines after bark beetles](https://battleborntreeservice.com/guides/removing-dead-pines-bark-beetles/)