In Missouri the oak timberworm Arrhenodes minutus (Drury) makes “pin holes” that degrade or even destroy the value of potential products obtained from many oak trees. The eggs are laid in blazes and other wounds that expose the bare wood on living trees. The larvae make their galleries across the grain of the wood, and they keep them clean by pushing borings, et cetera, out of them through hair-sized holes made in the wood by the parent females. The life cycle was 2 years for 3 specimens, 3 years for 122 and 4 years for 1 specimen. Pupation takes place near the exit from the larval gallery. No evidence of attack was found in black and scarlet oak trees that had not been wounded, but attacks were made through wounds in approximately 50% of the trees that were blazed in March, 78% of those blazed in May, 60% of those blazed in June, and 14% of those blazed in late July. In general, wounds less than 3 weeks old seemed to be more attractive sites for egg deposition than older wounds, but in a few instances eggs were laid in wounds that were 2 years old. However, eggs were not laid in wounded trees that were under 5.5 inches in diameter at breast height regardless of the age of the wound.