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Araneus Diadematus: The One-Year Life Cycle of the Cross Orb Weaver Spider

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An Adult Female Araneus diadematus, or Cross Orb Weaver

An Adult Female Araneus diadematus, or Cross Orb Weaver

A Stand-Out Spider

Often found calmly perched at the center of their sparkling, radial webs in gardens across Europe and North America, cross orb weavers (Araneus diadematus) are among the most visually striking and kinetically graceful spider species frequently observed in urban settings. Other common names for the species include the European garden spider, crowned orb weaver, and pumpkin spider.

Female cross orb weavers are easily identified by their robust abdomens, which can vary in color from mottled light beige to burnt orange to dark brown but almost always feature two series of white dots that intersect perpendicularly to one another, forming the impression of a cross. These white spots are comprised of guanine, the same material responsible for the white appearance of some bird and bat droppings. Also notable are the spiders’ legs, each of which is comprised of seven distinct segments lined with small sensory hairs that give the spiders an unshaven appearance.

Early Life (Late Fall Through Early Spring)

A cross orb weaver’s life begins among siblings. After being laid in the fall, hundreds of eggs nestle in stasis throughout winter within a squat, protective egg sac. These silk-based incubators are comprised of a short, cylindrical chamber capped by two disc-shaped plates. Egg sacs are generally deposited under leaves or bark or nestled in protected corners or eaves.

As temperatures begin to rise in early spring, heat instigates the maturation process, and the cross orb weaver spiderlings emerge from their eggs. At this stage, the spiderlings usually appear bright yellow except for a small, black area situated on the hindmost portion of the abdomen.

A Group of Recently Hatched Juvenile Cross Orb Weavers

A Group of Recently Hatched Juvenile Cross Orb Weavers

Once they have emerged from their egg sac, the young orb weavers begin to disperse gradually via a method known as "ballooning." Still extremely lightweight, the spiderlings extrude thin strands of silk from their spinnerets to act as sails. These strands catch the breeze and lift the spiderlings into an aerial commute that can range in distance from meters to kilometers. Each spiderling eventually lands in a strange, new environment in which it must begin the next stage of its life.

Middle Life (Summer)

Once a cross orb weaver completes its descent from its ballooning journey, its life as an independent, young-adult spider begins. Now alone, the young spider builds its trademark web. The webs created by cross orb weavers are highly geometrical, exhibit radial symmetry, and are built across a single plane (in contrast to the three-dimensional tunnel webs and cobwebs constructed by some spider species).

Cross orb weavers anchor their webs to anything available, commonly enlisting the aid of twigs, posts, walls, bushes, and the ground to keep their webs in place. Webs constructed by cross orb weavers tend to have between 25 and 30 radial lines of silk that extend from the web’s center, or "hub," to its perimeter.

Generally, cross orb weavers' webs are oriented perpendicular to the ground such that airborne insects are likely to fly into them when traveling laterally. Once an insect has been ensnared in its web, an orb weaver will rush to it and bite it immediately. The spider’s fangs inject a paralytic substance into the body of the insect, rendering it less able to defend itself (and potentially injure the spider in the process). This same substance causes the interior of the insect to liquify so that the spider can consume it after it has been wrapped in silk for storage. Depending on an orb weaver’s hunger level and the availability of prey, it may consume the liquified internal structures of a wrapped insect shortly after catching it or store it for later consumption.

Cross orb weavers exhibit sexual dimorphism when mature, meaning male and female specimens differ noticeably in appearance. At maturity, males are smaller than females and have less rotund abdomens. While both male and female cross orb weavers build webs to catch prey, males cease to do so once they reach maturity, opting instead to wander in search of female orb weavers to inseminate.

A male cross orb weaver may breed with multiple females, but a female orb weaver only needs to breed once. As with many spider species, female orb weavers have a propensity to eat their mates, generally before or after copulation, making the act a risky one for their male counterparts.

Once a female cross orb weaver has mated, she uses seminal vesicles to store the sperm she has acquired until she is ready to lay her eggs in the fall. Until then, she continues to sit at the hub of her web or hidden in nearby foliage, awaiting the vibration of a "trip line" of silk that signals the arrival of prey.

To ensure their continued efficacy, the webs of cross orb weavers are often consumed, recycled, and rebuilt by their inhabitants. When recycling their webs, orb weavers disassemble the structures, role them into conveniently consumable balls of silk, then eat them and reuse the silk proteins when producing subsequent webs.

An Adult Female Cross Orb Weaver

An Adult Female Cross Orb Weaver

End of Life (Late Summer/Early Fall)

As summer begins to wane and temperatures start to fall, female cross orb weavers prepare to lay their eggs, which can number in the hundreds. Once ready, soon-to-be mothers depart from their webs for the last time. Some individuals may consume their web to replenish their silk-protein supply before creating their egg sac. Once this is done, individuals often retreat to covered areas for several days.

Once an appropriately protected location is selected, the expectant orb weaver begins to construct her egg sac. This process begins with the fabrication of a basal plate, which serves as one of two "caps" to the cylindrical egg sac. Abdominal movements mold silk produced by an individual’s spinnerets into an appropriately sized disc. Once this is done, the spider crawls under the disc and continues to produce silk while spinning in circles to create a cylindrical wall beneath the first cap. After a brief rest, the spider begins to deposit her clutch of eggs into the silk cavity she has created.

Once her eggs have been successfully deposited, the orb weaver covers the open side of the egg sac with silk, creating a second cap and sealing the chamber entirely. Next, she wraps silk around the entirety of the structure to fortify it as much as possible to prepare it to lay unguarded through winter. The new mother will remain close to her egg sac for the next few days if any tears emerge that require repair. Several days after completing her egg sac, the new mother stops moving for good.

An adult female cross orb weaver

An adult female cross orb weaver

Additional Information About Araneus diadematus

  • Like other orb weaver species, diadematus’ venom is not medically significant to humans.
  • Due to the small size of their mouthparts and their preferred diet, orb weavers will rarely—if ever—bite humans.
  • Adult male cross orb weavers are observed far less often than females because they are smaller, have shorter lifespans, and do not build or occupy webs once they mature.

Questions & Answers

Question: What do spiders do in winter? Do they sleep?

Answer: Araneus diadematus generally die during the early part of winter. If one happens to be living indoors, it may survive a while longer.

Question: I just discovered a huge web inside my vehicle across my entire windshield. This huge web was spun overnight. Two days later another is spun across my back hatch door with a very large Araneus diadematus roosting in it. It’s October, what are the chances it laid eggs in my vehicle?

Answer: It's hard to say, but it's definitely possible. You can always examine the nooks and crannies near where the spider built her webs and see if you notice a disc-shaped egg sac anywhere. If you don't find anything, there's probably nothing to find. In any case, they are totally harmless, so even if a brood of baby orb weavers emerges in the spring, they'll likely just mull around for a bit before parachuting off to who knows where.

© 2019 Jeremy S


Viktor on November 11, 2019:

i have Araneus diadematus and she lives in a small space but since she laid eggs something doesn't move but just sit in the corner and dont move and when i touch it she moves but just near???