Tooth Digging Cryptocercidae

Cryptocercus spp. chew irregular tunnels in rotted logs, but the tunnels are clearly more than a by-product of feeding activities. Numerous small pieces of wood are obvious in the frass pushed to the outside of the gallery. When entering logs, the cockroaches often take advantage of naturally occurring crevices (knotholes, cracks), particularly at the log-soil interface. Burrows then generally follow the pattern of moisture and rot in individual logs. Rotted spring wood between successive annual layers is often favored. In well-rotted logs, the cockroaches will in part mold their living spaces from damp frass. In fairly sound logs, galleries are only slightly larger than the diameter of the burrower, and may be interspersed with larger chambers (Nalepa, 1984, unpubl. obs.).

Adult Cryptocercus have been observed manipulating feces and loosened substrate within galleries. The mate rial is pushed to their rear via a metachronal wave of the legs. The insect then turns and uses the broad surface of the pronotum to tamp the material into place. The tarsi are relatively small, and stout spines on the tibiae serve to gain purchase during locomotion. The cockroach is often upside down within galleries, and like many insects living in confined spaces (Lawrence, 1953), frequently walks backward, allowing for a decrease in the number of turning movements. The body also has a remarkable degree of lateral flexion, which allows the insect to bend nearly double when reversing direction in galleries (CAN, unpubl. obs).

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