Firewood Insects

You may notice sawdust piles developing on or under firewood that has been indoors for several days. You may even find some insects that have emerged from them. While this may be alarming, these are not rare events and seldom pose a problem.

Figure 1. Sawdust from insects present when the infested tree was felled. (Photo: D. Dougherty, USDA-APHIS)

Figure 2. Cross section of borer tunnels in firewood. (Photo: Dougherty, USDA-APHIS)


Many insects develop in stressed, dying, or dead trees, which is the very reason most are cut for firewood. Other insects seek shelter under loose bark or in cavities in the wood. A few days indoors can “bring them back to life.”

Beetles are the most common group found in firewood. They range from species that tunnel just beneath the bark to those that chew deep into the heartwood. Their activities ensure that the resources in dead trees are broken down and recycled. Their development usually continues to completion even after the tree is cut and split.

Figure 3. Many wood borer larvae are legless with soft white bodies and distinct dark heads. They can be found when splitting logs. (Photo: B. Wilson, Pulaski County Extension agent)

Figure 4. Brightly marked longhorn beetles are common insects that emerge from infested firewood stored indoors (Photo: Lee Townsend, UK).

Figure 5. Log riddled with small round emergence holes caused by bark beetles (Photo: Lee Townsend, UK).


Short term

It is normal to have insects in or on firewood. In the short term, minimize issues by:

  • Knocking logs together sharply to dislodge attached insects and brushing off any obvious structures, such as webbing or cocoons, before bringing wood inside.
  • Bringing only small amounts of wood indoors at a time and burning logs within a day or two. The longer “infested” firewood is indoors, the more likely its residents will resume their normal activities.


Do not treat firewood with insecticides

Sprays are ineffective and unnecessary. In addition, dangerous fumes may be produced when the wood burns.

Between season tips

Tips for managing firewood between seasons

  • Stack wood in a well-drained site and do not allow direct contact with the ground. This will reduce potential problems with termites.
  • Stack wood to allow good air circulation. Expose cut ends to promote drying. Expose bark covered surfaces to the elements because they are better able to withstand weathering.
  • Keep stored wood away from the house or other buildings.
  • Use the oldest wood or wood showing signs of infestation first, it is most likely to be infested. Avoid stacking new wood on top of last season’s wood.
  • Cover wood during summer and fall to keep it drier and to exclude creatures seeking protected overwintering sites.


By Lee Townsend, Extension Entomologist




Posted in Household Pests