|Foreign grain beetle, ventral view.|
Photo: S. Ciano
Foreign grain beetles are small beetles, only about 1/12 of an inch in length and brown in color. They live in damp areas where fungus grows and get the "grain" in their name when found in moldy, wet grain.
While they may be alarming to find in large numbers, they aren't damaging to the structure of the house. Foreign grain beetles are just a nuisance. They will not infest other items of the house, but if moisture continues to persist due to leaky pipes, leaks in the roof, etc., they have no reason to leave.
Foreign grain beetles are common in new construction and remodels, when drywall doesn't dry properly or wood gets moist either due to excess rain (what we've experienced this spring and early summer!) or extreme humidity (something we often see in the South Central Texas area).
They can be found in older homes if moisture, mold or fungal growth are issues.
To manage them, you must dry things up! Improve ventilation, use dehumidifiers, check for leaks in plumbing and excess moisture build up around foundations. Once the moisture source is reduced, the beetles will clear up on their own. Since they can be living inside walls, it is difficult for a pest management profession or you to manage them with residual pesticides alone.