Department of Entomology
|Fact Sheet on Powderpost Beetles and Wood-Inhabiting Fungi||
Insect Note - ENT/rsc-19
The term "powderpost beetles" refers to several groups of small woodboring beetles. In North Carolina, our primary concern is with anobiid ("an-oh-be-id") powderpost beetles, which attack the softwood species (conifers), such as spruce, pine and fir that are commonly used to make floor joists, wall studs and other structural lumber. Lyctid ("lick-tid") powderpost beetles attack only hardwoods, such as oak, ash, hickory, and maple. They tend to be a problem with antique furniture, cabinets, wooden floors and some interior moldings/trim in houses. Infested wood may look fine on the outside with no real evidence of an underlying problem.
Powderpost beetles lay their eggs in cracks, crevices or wood pores, preferably in unseasoned and unfinished (no paint or stain coating). The hatching larvae (immatures) feed primarily in the sapwood (outer lighter-colored wood). The name "powderpost" refers to the type of damage caused by the beetles. As the larvae feed, they produce the characteristic flour-like fecal material or "frass". Anobiids usually take 2+ years to complete their life cycle. Lyctid beetles may complete their life cycle in as little as three months, but more typically 9-12 months (or longer). We rarely find the actual beetles and only months or years later do we discover the damage. Typically, the only indication of a powderpost beetle infestation are small round holes about 1/32 - 1/16 inch in diameter scattered over the wood surface (as seen in the accompanying picture). In some cases, only one or a few boards are infested. In other instances, several joists may show sign of powderpost beetle activity. At first sight, people often assume that these holes are made by insects boring into the wood. The holes are actually made by adult beetles exiting the wood after they complete their life cycle. As the beetle emerges from the hole, it pushes out frass (yellow arrows in image) that will be found streaming from these holes or on the ground beneath the infested boards or surrounding the holes on horizontal wood. The frass of the lyctid beetles looks and feels like talcum powder. The frass of anobiid beetles is powdery but has a gritty texture. Frass that is yellow and caked is usually considered to be "old" and likely an indication an infestation that is no longer active. You may find exit holes and frass almost any time of the year, particularly in heated buildings or in crawlspaces. However, the peak time to watch for emerging beetles occurs in May through August.
You cannot simply look at a piece of wood to determine if the damage is severe enough to require repair or replacement. Probing the wood may give you some indication of the extent of the damage. If you are concerned about the condition of structural wood, such as floor joists, you may need to contact a general contractor or structural engineer.
Fungi Associated with Wood
There are several types of fungi associated with wood, but not all of them actually cause damage.
Surface Mold and Mildew
Brown Rot and White Rot
Pest information and control recommendations presented here were developed for North Carolina and may not be appropriate for other states or regions. Any recommendations for the use of chemicals are included solely as a convenience to the reader and do not imply that insecticides are necessarily the sole or most appropriate method of control. Any mention of brand names or listing of commercial products or services in the publication does not imply endorsements by North Carolina Cooperative Extension nor discrimination against similar products or services. All recommendations for pesticide use were legal at the time of publication, but the status of pesticide registrations and use patterns are subject to change by actions of state and federal regulatory agencies. Individuals who use chemicals are responsible for using these products according to the regulations in their state and to the guidelines on the product label. Before applying any chemical, always obtain current information about its use and read the product label carefully. For assistance, contact the Cooperative Extension Center in your county.
Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
(Photograph of Poria damage courtesy of K. Spillman, Innovative Pest Solutions, Raleigh, NC)
Last updated - Sept. 2005
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