Phosphaenus hemipterus (Goeze, 1777)
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POLYPHAGA Emery, 1886
ELATEROIDEA Leach, 1815
LAMPYRINAE Latreille, 1817
PHOTININI LeConte, 1881
Phosphaenus Laporte, 1833
So far as is known this is the only member of the family with consistently flightless males and females, males are brachypterous and females are apterous. The species is native to the Palaearctic and widespread though generally uncommon throughout Europe from the Mediterranean to southern Scandinavia, and from Spain to Russia, in some areas it is very rare and thought to be in decline e.g. in Germany it is considered to be endangered. Several large, widely spaced and thriving populations have become established in Nova Scotia where it was first discovered in 1947 and are thought to result from several separate imports of gravel or horticultural and agricultural material from Europe during the nineteenth century. In the UK it is considered to be adventive; it was first discovered towards the end of the nineteenth century at a few sites in Hampshire and Sussex and until recently there were very few further records, mostly many years apart and all from southern near-coastal locations. In 2007 a colony was found in South Hampshire which since that time has been thriving, and since then further specimens have been recorded from Kent, North London and North Wales.
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On the continent it is a species of floodplains, meadows, dry hillsides and forest borders and is occasionally recorded from parks, gardens and other disturbed habitats such as graveyards and lawns, it prefers open and loamy soils with patchy and dense vegetation, typically near field margins, copses and hedgerows. Adults occur during May and June or a little later depending upon the season, they are diurnal although mainly crepuscular, and communicate with hormones; males detect females from up to 20 metres and approach from downwind. They are short-lived, 1-2 weeks, and do not feed, when alarmed both sexes will glow, each with 2 small lamps near the abdominal apex, but this is only dim and generally not helpful when searching for them. Both sexes are difficult to find but especially the females which tend
to remain concealed, males roam open areas and will occasionally climb grass stems or the base of walls or trunks waving their antennae to detect female pheromones, and have sometimes been found on pathways or bare soil. Larvae occur in the same habitats as the adults, they are similar to Lampyris larvae but smaller, more slender and lack the lateral series of pale markings, they develop over 2 or 3 years and are obligate earthworm feeders; when presented with molluscs etc. in the laboratory they were ignored but earthworms were always taken, and they can predate worms much larger than themselves, stunning them with digestive enzymes through sharp and grooved mandibles. Males have been found by sweeping low vegetation and both sexes have been taken at pitfall traps.
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Both sexes are distinct among our fauna; the male is brachypterous with short diverging elytra that cover at most part of the first two abdominal segments while the female is apterous. The male is easily separated from our other lampyrids by the long and stout antennae and quadrate pronotum, in our other lampyrids the antennae are more slender and shorter and the pronotum is transverse. The female is entirely drab brown, smaller and lacking the lateral luminescent organs of Lampyris, and without the translucent pronotal window seen in both sexes of Lamprohiza.
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Further to the above, during June 2022 several adults were found (and filmed and placed on facebook) on the shore of Derwentwater in the Lake District by Mark Phillips, this is about as far as it’s possible to get in England from the known sites in the south, so maybe the species will become widespread in future. In any case a significant find so thanks to Mark and Lisa.