Bridge spider
Larinioides sclopetarius
The bridge spider is a prominent orb-weaver known for its preference for man-made structures such as bridges and buildings near water bodies. It features a flattened abdomen with a characteristic dark-edged folium pattern. This species is notably nocturnal, often exploiting artificial light sources to capture attracted prey. Their webs can reach significant sizes and are frequently found in high densities at suitable locations.
Details
Identification
Dark folium pattern on the opisthosoma, flattened body shape, heavily haired, often grey-brown coloration with light banding on the legs.
Social behavior
Primarily solitary, but shows high tolerance towards conspecifics in areas with high prey density (aggregation formation near light sources).
Diet
Mainly flying insects, especially midges (Chironomidae) and caddisflies.
Hunting strategy
Construction of large orb webs, often directly on illuminated structures to exploit the attraction of light for insects.
Spawning substrate
Egg sacs are deposited in protected crevices of buildings or within vegetation.
Overwintering
Overwinters as a juvenile or within the egg sac in protected crevices of buildings or under bark.
Ecology
Ecological role
Important predator of aquatic insects in their terrestrial stage; link between aquatic and terrestrial ecosystems.
Natural predators
Insectivorous birds, spider wasps, ichneumon wasps, and larger spider species.
Competitor species
Furrow orb-weaver (Larinioides cornutus), European garden spider (Araneus diadematus).
Ecosystem service
Natural pest control by reducing mosquito and fly populations in urban areas.
Threats
Renovation of bridges and buildings, use of insecticides, extreme light pollution.
Scientific profile
Profile
Distinguishing features
Larinioides sclopetarius is characterized by the very sharply defined folium on the abdomen. Compared to L. cornutus, the pattern is usually darker and more contrasty. The species is strongly synanthropic and almost exclusively found on man-made structures like bridge railings. Scientific identification often requires examination of genital morphology (epigyne/palpal bulb).
Habitat
Strongly hygrophilous and synanthropic; prefers vertical surfaces on bridges, locks, fences, and buildings in immediate proximity to running or standing water bodies.
Role in food web
Important predator for aquatic insect populations; serves as food for birds (e.g., wagtails) and specialized spider wasps.
Protection & threats
Main threats
No known threats at present; the species benefits from anthropogenic structures and light pollution.
Population trend
Stable to increasing; widely distributed throughout Europe, especially in urbanized river landscapes.