Melanophila acuminata (De Geer, 1774)
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POLYPHAGA Emery, 1886
BUPRESTOIDEA Leach, 1815
BUPRESTINAE Leach, 1815
MELANOPHILINI Bedel, 1921
MELANOPHILA Eschscholtz, 1829
This is probably the most widely distributed member of the family; the distribution is Holarctic extending north to Sweden and Canada and south to North Africa and the Caribbean where it was probably introduced. It is common or even abundant through most of its distribution although in Europe it is sporadic and rare in many places. In the Nearctic region adults are often attracted to forest fires in huge numbers and it seems that most species of conifer are used as hosts, in Europe generally they are less common and this may be due in part to the efficiency with which fires are controlled and the commercial nature of softwood forestry in general. The first U.K. record was from Surrey in 1909 and over the following two decades there were a few records from Hampshire, Berkshire, Kent, Devon and Dorset; there have been very few records since the 1980’s ad it may now be extinct. Larvae were found in Surrey during the 1970’s and 1980’s so confirming its status as a breeding resident but it is possible that the majority of records are based on specimens arriving by flight from the continent.
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Adults are strongly attracted to burning live conifer trees; in Europe typically Scott’s Pine, and Birch has also been recorded, often from long distances so that swarms may gradually build up, leading to one observation of them occurring in ‘sometimes unbelievable numbers’. Beyond these conditions they are rarely seen in the wild. They occur from May to September and are diurnal, they use olfactory senses to detect fires but they are also attracted to infra-red from hot surfaces, a potentially disastrous behaviour in industrialized areas. They mate soon after arrival and as soon as the flames have subsided the females oviposit in the bark, usually on the most severely burnt areas and often while they are still smouldering. First instar larvae feed within the bark and here they overwinter, later instar larvae bore into the xylem and spend another year or two developing before they pupate, generally in the spring. Adults emerge from typical buprestid D-shaped holes in late spring. The species is completely dependent upon burnt trees for its survival and the adults will continue to visit burnt timber for up to a year after a fire.
Among the U.K. fauna this large and shiny-black beetle is distinctive; it is the only species of the family with the elytra produced into a point. 8.0-11.0 mm. The dorsal surface is glabrous, the ventral surface with pale setae. Head transverse with prominent eyes and two transverse impressions on the frons; vertex punctured, frons with polygonal microsculpture. The pronotum is transverse with rounded or weakly angled lateral margins; anterior angles produced and the basal margin bisinuate, disc punctured, lateral margins with polygonal microsculpture. Median longitudinal impression distinct, at least towards the base. Scutellum small and transverse. Elytra broadest in the apical half then strongly narrowed to the apex; surface granulate and uneven giving a very distinctive appearance, very close to charcoal. Males have the inner margin of the mid-tibiae weakly serrate and the terminal abdominal sternite is deeply incised; the female tibiae are smooth and the terminal sternite is only shallowly incised.
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Melanophila Eschscholtz, 1829
Fire Beetles
Depending upon how the genus is defined it is now generally considered to include about 16 species; it was formerly much larger, including more than 70 species with many from the Nearctic and Neotropical areas but it has now been split up into several genera. Members are small to medium sized buprestids and the common names refer to their exceptional sensitivity to infra red radiation and attraction to burning trees although not all behave this way e.g. the Canadian M. flavoguttata (Harris, 1829) develops under the bark of various conifers that have been damaged by drought or infestations of other insects. The genus is Holarctic, extending south to the Caribbean and, in the case of one species, to South Africa; most have a wide distribution, no doubt due to their superb ability to disperse, and they are quick to become established in new fire-damaged areas of appropriate woodland or wooded moorland etc. The species are either all dark or dark with various pale markings which make them cryptic against charred wood; see M. consputa LeConte, 1857. It is thought the larvae of most species depend on the wood of freshly burned trees because they cannot cope with the tree’s natural chemical defences, the charred bark also being relatively free of parasites and predators. The adults are strong fliers and arrive quickly at freshly scorched or still burning or smouldering trees, mostly conifers but also some broadleaved species e.g. Betula, often in large numbers where they aggregate on the timber or swarm around smouldering stumps etc. They quickly mate and the females oviposit into the bark, even when it is still smoking, where the larvae initially feed, moving into the xylem when they are larger. Adults can detect and fly towards fires from long distances, beyond 25km, using a combination of olfactory sensors in pits on the antennae, and infra-red sensitive organs in pits on the metathorax; these may be able to detect infra-red from up to 80km.
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The species are medium sized, up to 15mm, flattened dorsally and drab or with pale macula and variously metallic. They generally resemble the charred host material. The eyes are prominent and the clypeus emarginate and sharply angled anteriorly, the antennae are at least to some extent serrate from the fourth segment. The pronotum is punctured and/or transversely wrinkled with the basal margin strongly bisinuate, and the elytral apices are produced. The basal segment of the metatarsus is at least as long as the next two together.