Bridge-spider, Gray cross-spider
Larinioides sclopetarius, commonly called bridge-spider or gray cross-spider, is a relatively large orb-weaver spider with Holarctic distribution. These spiders originated in Europe, have been observed as south as the Mediterranean Coast and as north as Finland, and have been introduced to North America. They are often found on bridges, especially near light and over water. The species tends to live on steel objects and is seldom seen on vegetation. Females reach a body length of 10–14mm, and males 8–9mm. Their orb webs can have diameters of up to 70 cm.
L. sclopetarius is attracted to light. Spiders found near light sources may be in better condition and have greater reproductive success than spiders living in unlit areas. Most of these lighted areas are found in cities or other metropolitan areas. As a result, many urban areas have become saturated with these spiders. As many as 100 of these spiders can be found in a square meter in optimal feeding locations.
L. sclopetarius often hide during the day, and wait for prey in the center of their web at night. In high-density populations, spiders may remain sedentary to protect their territories. Mature females and juvenile spiders will often build webs. However, adult males generally inhabit adult female webs. Males can be found mostly during summer, while females are active until November in Central Europe.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withL. sclopetarius exhibit a slight sexual dimorphism, where females are heavier than males. Females typically weigh around 60 mg, whereas males weigh around 38 mg. However, males may be slightly larger than females. Females can range from 4.5- 6.25 mm in length. Males vary from 4.25 mm -7 mm in length.
L. sclopetarius differs from its close relatives, L. patagiatus and L. cornutus, with a few defining characteristics. Unlike the latter two species, L. sclopetarius has white hairs that provide a silhouette for their heads and dark markings on its abdomen.
In North America L. sclopetarius is most common in the Great Lakes states, but can be found throughout the country. It is mostly found near buildings. L. sclopetarius is also found in Central Europe, often near water. They are also most commonly found near artificial sources of light near water bodies such as bridges and boats. They often aggregate in high densities near light sources. The lights tend to attract more insects which increases the spider's prey capture. Their light-seeking behaviors may have some genetic basis.
In these feeding-locations, adult females tend to occupy the best foraging areas. Juveniles and immature spiders are relegated to worse feeding areas when competition is high. These behaviors may be observed because to juveniles are unable to compete for better territories. However, when these spiders mature, they often search for more illuminated areas to create their webs and lay their eggs.
L. sclopetarius is not a social spider. However, they often build webs next to each other. Females exhibit territorial defense of their webs from intruders, including other members of the same species. In high population densities, females exhibit more aggressive behavior to conspecifics due to the shortages of territories.
Female spiders live independently, defending their own webs. However, male spiders may have a kleptoparasitic relationship with a female. They often choose to live on a female's web and steal their prey.
L. sclopetarius exhibits high levels of activities in unfamiliar environments, which may have contributed to their widespread colonization of urban areas. In experimental conditions, they tend to move and explore new settings more than their other urban counterparts Zygiella x-notata.
L. sclopetarius exhibits many aggressive behaviors such as chasing and attacking conspecifics. If individuals are in the same web, they may engage in web-shaking contests. These aggressive behaviors may be genetically inherited. Males are generally more aggressive than females (https://link.springer.com/article/10.1007/s00265-017-2353-x).
L. sclopetarius typically positions itself on the lower areas of the web. This can be seen as a defensive behavior as it allows the spider to easily escape from the web from predators by using a safety line.
L. sclopetarius moves between areas using a ballooning technique where the spider releases threads into the wind to travel. This method allows the spider to travel to preferable feeding areas.
These spiders are primarily nocturnal foragers. Their prey capture fluctuates with the seasons. Their prey capture is highest in the summer months, declining in the spring and fall. Chironomids consist of a significant portion of their diet. These small flies may comprise up to 94% of the spiders’ diets. Their prey's average size ranges from 1.2 to 6.8 mm.
Assortative mating may be at play, as aggressive males and females are more likely to mate with each other. Additionally, non-aggressive individuals are more likely to mate with each other. Aggression may be selected for as it may be important for securing the best sites for web building, which are around light sources. In some instances, groups of aggressive spiders may have lower mortality rates than mixed groups with non-aggressive and aggressive spiders.
Aggressive males tend to create more fit males. Female reproductive success was partially dependent on female size rather than aggressiveness.
