Micromalthidae

The telephone-pole beetle (Micromalthus debilis) is a beetle native to the eastern United States and the only known living representative of the otherwise extinct family Micromalthidae. Larvae of the beetle live in decaying wood and can be pests to wooden structures, lending them their common name, the 'telephone-pole beetle.' The larvae of Micromalthus debilis start as tiny white creatures with well-developed legs, resembling carabid larvae. Larvae bore into moist, decaying chestnut and oak logs, creating galleries as they consume wood fibers. Adult beetles are dark brown to blackish with vestigial reproductive organs. Micromalthus's evolutionary history dates back millions of years, with fossil records found in various ambers. Their larvae infest timber, weakening structures and attracting fungi, as seen in South African gold mines in the 1930s. The telephone-pole beetle used to have reproducing adults, but has evolved to become obligately paedogenetic, having asexually reproducing (parthenogenetic) female larvae and sterile adults that occasionally develop from the juveniles. The rare adult is sometimes referred to as a 'ghost adult' due to its vestigial existence. When a substantial number of adults are generated at once in laboratory experiments, they exhibit vestigial mating behavior, including sex-role reversal, with females exhibiting more aggression and competition for mates. Being one of few parthenogenetic haplodiploid species, the telephone-pole beetle is an interesting subject of coleopteran reproductive behavior and physiology.