grub in the wood
Location: houston, texas
May 2, 2011 10:24 am
I had a water oak that died a year ago. I chopped it down and was splitting the wood for firewood. This grub fell out. It was burrowed in the middle of the log and is about 2 and half inches long. What is it, and could it be the reason the tree died?
This is the larva of a beetle in the family Cerambycidae, the Longhorned Borers. The Larvae are known as Round Headed Borers. You can compare your images to those posted to BugGuide. The BugGuide information page indicates this about food: “Larval habits: Most species feed within dead, dying or even decaying wood, but some taxa can use living plant tissue. Girdlers (adults of the Onciderini, larvae of genera in the tribes Methiini, Hesperophanini and Elaphidiini) sever living branches or twigs, with the larvae developing within the nutrient-rich distal portion. The larvae of a few species move freely through the soil, feeding externally upon roots or tunneling up under the root crown.” BugGuide goes on to reveal this about the life cycle: “The life spans in temperate regions typically range from 1 to 3 years, but cycles of 2-3 months to decades have been documented. Most of the lifetime is spent in the larval stage; the adults usually emerge, disperse, reproduce, and die within a few days to months. Cellulose digestion appears to be aided primarily by enzymes rather than symbiotic microorganisms. In many cases, Cerambycidae are primary borers, providing a vital ‘first step’ in the biorecycling of wood.” The other major family of wood boring beetles are the Metallic Wood Borers in the family Buprestidae. The Buprestid Larvae are known as Flat Headed Borers. You may compare the Round Headed Borers to the Flat Headed Borers by looking at these images on BugGuide. Except in rare cases, Borers feed on dead and dying wood and they do not infest the wood of healthy trees, so we doubt that the death of the tree was caused by this Round Headed Borer.