Arthropods •

Telephone-pole beetle

(Micromalthus debilis)


The telephone-pole beetle (Micromalthus debilis) is a beetle native to the eastern United States, and the only living representative of the otherwise extinct family Micromalthidae (i.e., a "living fossil"). Classification of M. debilis was historically controversial and unsettled. The species, first reported by John Lawrence LeConte in 1878, was long considered one of the Polyphaga, and placed in the Lymexylidae or Telegeusidae, or as a family within the Cantharoidea. However, characteristics of larvae, wings, and male genitalia show that it is in the suborder Archostemata, where it has been placed since 1999. The beetle is elongated, ranging from 1.5 to 2.5 mm (0.059 to 0.098 in) in length, and a dark brown to blackish color, with brownish-yellow legs and antennae. The head is larger than the thorax, with large eyes protruding from either side. The larvae are wood-borers that feed on moist and decaying chestnut and oak logs. They have also been reported as causing damage to buildings and poles (hence the name). The life cycle is unusual in that the cerambycoid stage of the larva gives birth via parthenogenesis to caraboid larvae, or more rarely, develops into an adult female. The adults of both genders are sterile, and are likely vestigial remnants of a time when the lifecycle involved sexual reproduction. Fossils of the genus are known from the Miocene aged Dominican amber (adults and larvae, which were found to not be distinguishable from the living species) and Mexican amber (larvae), the upper Eocene Rovno amber of Ukraine (Micromalthus priabonicus), the early Eocene (Ypresian) aged Oise amber of France (Micromalthus eocenicus) The oldest record of the family is Archaeomalthus from the Upper Permian of Russia over 250 million years ago, which is morphologically similar in many respects to Micromalthus. Reports of the species are infrequent and it is unknown whether they are rare, or common and unrecognized. A recent study by Bertone et al. (2016) found telephone-pole beetles in a survey of the indoor arthropod fauna in 50 houses located in and around Raleigh, North Carolina. A recent survey found that the species had spread to every continent except Australia. With finds in South Africa, Hong Kong, Belize, Cuba, Brazil, Japan, Hawaii, Italy and Austria, the dispersal is likely connected to the timber trade.

Taxonomic tree:

Kingdom: Animalia
Class: Insecta
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