Lamprohiza splendidula is a glow-worm with a widespread distribution across Europe. We assign it to the category of Least Concern, based on its wide distribution and rather broad habitat use. However, populations may be susceptible to local extirpation, as this species needs undisturbed microhabitat of shaded moist vegetation and leaf litter layers to complete its life cycle. It is also threatened by light pollution, as courtship in this species involves dim, light-based courtship signals that may be disrupted by even low levels of light pollution.

Lamprohiza splendidula has a widespread distribution across Europe. It is known from Belgium, the Netherlands, and France. In central Europe there are records from Luxembourg, Germany, Poland, Slovakia, Czech Republic, Austria, parts of Switzerland, northern Italy, Slovenia, Hungary, Croatia, Bosnia, Romania, Montenegro, and Serbia, with records from Ukraine representing the eastern edge of its distribution, and records from Lithuania, and the Kalingrad Oblast region representing its northern distributional limit. Historical records from England are thought to represent introduced specimens, and this species no longer occurs there.

The extent of occurrence (EOO) of this species, based on known extant occurrences, is almost 2 million km². The area of occupancy (AOO) is at least 6,672 km².

At present there are no studies that have investigated the population size or trends of this species.

Lamprohiza splendidula is typically found in moist, shaded habitats with at least a semi-developed shrub layer such as deciduous woodlands, the banks of rivers and streams, meadows, and gardens (De Cock 2009). A microhabitat with a well-developed leaf litter layer is also required for this species to complete its life cycle. (M. Novák and R. De Cock pers. comm. 2022).

The development of Lamprohiza splendidula takes two (Hůrka 2005) or possibly three years, during which three winters will be spent as a larva (Schwalb 1961). Larvae shine brightly and are visible from several metres away, however when handled they markedly reduce their glow (Novak 2018). Larvae are often encountered pressed closely against leaf litter with the legs and head hidden (Novak 2018). Larvae of this species generally feed on snails (Novák 2018) but will also feed from fresh carrion (Schwalb 1961). Pupation occurs in the spring with the pupa secreted under leaf litter, pieces of wood or stone in small open chambers excavated in the underlying soil (Schwalb 1961, Burakowski 2003). The pupal stage lasts for an average of 7 days (Schwalb 1961, Novák 2018). The pupae will wriggle when exposed to a strong light source, possibly to try and move to a darker place (Novak 2018).

Adults emerge from May to July and mating takes place until September, although maximal numbers are usually seen at the end of June (Magis 1977, Burakowski 2003, Hůrka 2005). The females of this species lack wings and thus cannot fly. Starting about 30 minutes after sunset, receptive females emit a continuous glow that can last for two to three hours or until the female is found by a male. Females use this glow signal to attract patrolling males (Schwalb 1961, De Cock 2009, M. Novák pers. comm. 2022), although courtship may also involve production of female sex pheromones (Novák 2022).

Males of L. splendidula become active about 30 minutes after sunset and start by flying short distances close to the ground (R. De Cock pers. obs., Novák and Jakubec 2024). As night becomes darker, the glowing males fly higher and further. Flying males may glow continuously (Schwalb 1961) or emit minute-long glows of variable intensity (De Cock 2009), though in Czechia males observed both in the field and in captivity appear to glow for only several seconds then turn it off, or at least reduce their glow intensity (M. Novák pers. comm. 2022). Males also glow continuously when they are trapped/stuck e.g. in a spider web (M. Novák pers. comm. 2022). Male activity lasts only 45-60 minutes; within two hours male activity has stopped completely (De Cock 2009). The purpose of the male glow is not clear, as in this species male light signals do not appear to be important in mate attraction (De Cock 2009); rather, bioluminescence in L. splendidula males may function in anti-predator defence (De Cock 2009) .

Adult males of Lamprohiza splendidula are attracted to artificial lights, and will preferentially approach brighter light sources (De Cock 2009). Schwalb (1961) reported that males were attracted to all light colours with a preference for blue light. However, De Cock (2009) found that males were difficult to lure to most lights, regardless of the colour; instead males are very picky and are preferentially attracted to green or yellow light of low intensity (R. De Cock pers. obs.).

Although specific threats to Lamprohiza splendidula have not been studied, fireflies in general are threatened by habitat loss and degradation, light pollution, and climate change (Lewis et al. 2020), all of which could impact this species.

Lamprohiza splendidula is predominantly found in deciduous woodlands and meadows, thus land use changes such as deforestation, agricultural intensification or property development are likely to be particularly damaging for this species, either due to destruction of their breeding sites or by fragmenting remaining habitat. Females of this species are wingless and have poor dispersal capabilities, which could restrict colonization of new sites, particularly where their habitat has been fragmented. At least in Czech Republic, the observed landscaping trend toward trimming or completely removing bushes from city parks and gardens in order to make people feel safer at night seems to completely extinguish firefly populations there (M. Novák pers. comm. 2022). Also, landscaping activity in general appears to reduce populations of these fireflies, as they are never seen in any parks with mowed grass, replaced or disturbed soils, even in sites with old trees and no light pollution (M. Novák pers. comm. 2022, R. De Cock pers. obs.).

Artificial light at night (ALAN) is a rapidly growing environmental threat: Earth’s satellite-observable light emission increased by nearly 50% from 1997–2017 and skyglow has been estimated to extend over 23% of terrestrial land area (Gaston and Sánchez de Miguel 2022). More than 98% of the European Union is affected by light pollution (Falchi et al. 2016). Replacement of monochromatic street lighting with LED light is an additional problem, as white LEDs are ~2.5 times more polluting than traditional lighting (Falchi et al. 2016). Such light pollution has pervasive impacts on the physiology and behaviour of individual organisms, the abundance and distribution of species, and the structure and function of communities and ecosystems. Because courtship behaviour and communication of L. splendidula relies on low-intensity bioluminescent signals, ALAN may have a negative impact on the reproduction of this species. In another European glow-worm, Lampyris noctiluca, considerable experimental research has demonstrated that light pollution, even at low intensities (less than 0.027 lux), is a major threat to glow-worm reproductive success (Ineichen and Ruttimann 2012, Elgert et al. 2021, Gardiner and Didham 2021, Van den Broeck et al. 2021a,b). If female-produced sex pheromones also help attract males in L. splendidula, then the effects of light pollution may be lessened. Additionally, because males fly higher and further under darker conditions, light pollution might limit male dispersal.

Climate change has altered precipitation patterns in Europe, resulting in an increase in the duration, intensity, and frequency of droughts, which will impact glow-worms that rely on moist microhabitats to prevent desiccation of all life stages. Pesticides may have deleterious effects on firefly adults and larvae, while molluscicides can reduce the availability of snail prey for glow-worm larval stages.

There are no known uses for this species.

This species may occur on regionally protected sites, and management of these sites should take into account the habitat requirements of this species. Consideration should be given to providing protection to other sites where this species is known to occur. Full consideration of this species should be given in land use change decision making. The use of pesticides on sites where this species occurs should be avoided.

Habitat connectivity is essential to reverse the declines of this species. The presence of continuous moist leaf litter layers between habitats is crucial as, except for gene flow by flying males, all other dispersal happens in the larval stage that only seems to move within moist microhabitats (R. De Cock pers. obs.). Wherever possible, suitable habitat should be established in the vicinity of existing sites. Light pollution is a major threat to the reproductive success of this species. Legally binding targets for the reduction of light pollution should be introduced throughout the species range. The network of dark sky parks and reserves should be expanded to cover more of the sites where this species occurs. Dark sky corridors could be developed linking suitable sites with those where the species is present.

More research in the form of detailed surveys and monitoring is needed in order to better understand to what extent land use changes and increasing levels and extent of artificial light will have an impact on the survival of populations of Lamprohiza splendidula and to describe a possible ongoing yet undetected decline of the species in Europe.