Nov 19, 2012 – Bugs In The Fireplace


I just found hundreds of little holes and really soft sawdust/frass in the firewood of my client. It's not carpenter ants. I took some pictures to show you. Can you help me identify this insect?


This time of year people bring firewood in from the outside and pile it next to the fireplace in anticipation of that first really cold night when a fire would be wonderful to warm the house. Or, perhaps they even store a large supply of firewood indoors for the winter so they are not having to go in and out every night, particularly in a northern region like yours in Ontario. Quite often that firewood was from a tree that was cut down or that died within the last year, perhaps early in the spring. Almost immediately after it dies beetles are going to discover this new food resource, since the role of most wood infesting beetles is that of recycling that dead wood back to sawdust. Or, option 2, the tree may have been infested with small bark beetles such as shot-hole borers. 

But, typically the beetles that feed within dead trees or logs will spend the winter in the pupa stage or late stage larva, and do not move to the adult stage until the warm days of spring. If that firewood were left outside the beetles would just remain in it until spring, but by bringing the wood indoors it warms up and triggers the dormant beetles to believe it is spring, and out they come, often leaving little piles of sawdust around the hole made by the adult beetle. 

You need to find some of the beetles, and window sills are a good first place to look. You also need to have this customer move that wood back outside until it is needed for the fireplace. If this is a hardwood of some kind these could be powderpost beetles, and these beetles do have the ability to move into structural wood materials such as hardwood floors or furniture or cabinets. Perhaps they are deathwatch beetles, which could be in either hardwoods or softwoods, and they too could infest other wood in the home. If they are bark beetles, most common in pines, then they will not infest wood in the home. A very close look at that frass might be helpful, as powderpost beetle frass is like fine powder, deathwatch beetle frass powder-like but more gritty, and bark beetles less likely to leave piles of frass lying around. 

But, very important right now is to move the firewood back outside and bring in only as much as is needed for immediate use. That will keep the beetles in the wood dormant, and when it finally is burned there could be a pleasant aroma of little tiny beetles cooking over the fire. 

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