Ponderous Borer – Ergates spiculatus

Ponderous Borer (Ergates spiculatus) Latin Name: Ergates spiculatus Common Name: Ponderous Borer, Spiny Wood Borer Beetle or Spine-Necked Longhorn Beetle Appearance: The ponderous borer is a big beetle with an elongated body that may grow 45-60 mm long. It is mostly dark brown; however, the wing coverings may be a lighter brown. The larva is a huge roundheaded borer creamy white except for the brown mandibles near the head. Host plants: Ponderosa pine and Douglas-fir are the principal hosts Damage caused by Ponderous Borer: The ponderous borer exclusively lives on fallen trees and poses little risk to landscaping plants. This is, however, the biggest species of wood-boring beetle discovered in Colorado, and its size draws notice. Life history and Habits: Adults can be seen from early June to late August. Females deposit their eggs in the cracks in the bark of dead pine trees and stumps. Over several years, the larvae construct huge tunnels into the sapwood and heartwood. This species like to feed on pine logs. The ponderous borer only grows on dead or dying trees and poses no damage to living trees. However, this is Colorado’s biggest insect, and its size frequently draws notice and worry. Foresters frequently refer to hefty borer larvae as “timber worms.”