Micromalthus debilis is also known as the “Telephone Pole Beetle” because it tunnels into logs and poles of buildings including telephone poles. It is a scientific curiosity because of its unique life history. Pollock and Normark* remarked, “Micromalthus debilis has one of the most bizarre life cycles.” This beetle can produce winged adults that mate and disperse, or it can reproduce parthenogenically as larvae.
Micromalthus debris larvae have several forms. The first instar is an active triungulin that walks using legs. This instar molts to a legless cerambycoid larva. This legless larval stage, may develop and reproduce in several ways. The larva can produce female triungulin larvae that are born alive. It can produce a single male egg. In this process, the egg hatches into a short legged curculionoid larva that devours its mother and becomes a haploid adult male. It can molt to a pupa and then to an adult.
It is not understood how the different types of development are controlled or the conditions that make one type of development more adaptive. Insects with bizarre life history are useful for asking question and understanding the advantage of life cycles and traits that are more typical.
*D. A. POLLOCK and B. B. NORMARK. 2002. The life cycle of Micromalthus debilis LeConte (1878) (Coleoptera: Archostemata:
Micromalthidae): historical review and evolutionary perspective. J. Zool. Syst. Evol. Research 40 (2002) 105–112