Although people are concerned about being bitten by these large spiders, they are not considered dangerous. They may bite when harassed, but apparently the venom does not cause problems for humans. (Lyon 1995)
The function of web stabilimenta is controversial. At least 78 species of spiders add these structures to their webs, originally named "stabilimenta" because they were thought to provide structural stability. One study of Argiope spiders supports the idea that these bright white structures attract flying insects (Tso 1998). Contrary to this "prey attraction hypothesis," hungry spiders build fewer or smaller stabilimenta, and webs with stabilimenta capture fewer prey (Blackledge 1998, Blackledge and Wenzel 1999). A competing hypothesis is that the highly visible threads prevent birds from flying through and destroying the webs. Spiders of another species, Octonoba sybotides, vary their stabilimenta in order to control thread tension. Different tensions allow a spider to detect prey of different sizes. However, this mechanical hypothesis doesn't explain why only diurnal spiders use stabilimenta. (Milius 2000).
These spiders have relatively poor vision, but are quite sensitive to vibration and air currents. Males communicate with potential mates by plucking and vibrating the females' webs.
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: vibrations
Perception Channels: visual ; tactile ; vibrations ; chemical
These common and widespread spiders have no special conservation status.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
In areas with a cold winter, the eggs of this species hatch in the late summer or autumn, but the hatchling spiders become dormant and do not leave the egg sack until the following spring. Hatchlings generally resemble small adults, there are no major changes in anatomy or structure as they grow (except the development of reproductive organs).
Development - Life Cycle: diapause
Researchers study the biochemistry of web production and venom action of this spider. Results from these studies may aid the fields of materials science and neurophysiology.
Argiope species are important predators of grasshoppers in rangeland ecosystems.
Like all spiders, black-and-yellow argiopes are carnivorous. They spin an orb web to capture small flying insects such as aphids, flies, grasshoppers, and Hymenoptera (wasps and bees). A female can take prey up to 47mm in diameter, up to 200% of her own size (Nyffeler et al. 1987)
The web can be up to two feet across. The spider hangs, head down, in the center of their web while waiting for prey. Often, she holds her legs together in pairs so that it looks as if there are only four of them. Sometimes the spider may hide in a nearby leaf or grass stem, connected to the center of the web by a nonsticky thread which quivers when prey lands in the web.
Web construction is complicated. To start the web, Argiope firmly grasps a substrate like a grass stem or window frame. She lifts her abdomen and emits several strands of silk from her spinnerets that merge into one thread. The free end of the thread drifts until it touches something far away, like a stem or a flower stalk. She then creates bridge lines, and other scaffolding to help her build the framework of the web. She builds a hub with threads radiating from it like a spokes of a wheel. She switches to sticky silk for the threads spiraling around this hub that will actually catch her prey. It may take a few hours to complete the web, then she eats the temporary scaffolding and the center hub. Argiope spiders often add stabilimenta, or heavy zig-zagging portions, in their webs. A stabilimentum may or may not aid prey capture (see below). The entire web is usually eaten and then rebuilt each night, often in the same place.
Animal Foods: insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore )
These spiders are found from occur from southern Canada south through the lower 48 United States, Mexico, and Central America as far south as Costa Rica.
Biogeographic Regions: nearctic (Native )
This species prefers sunny areas among flowers, shrubs, and tall plants. It can be found in many types of habitats, though is not common in the Rocky Mountains or the Canadian Great Basin.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest
Wetlands: marsh ; swamp
Other Habitat Features: suburban ; agricultural
In temperate climates, the great majority of individuals live a little over a year: from their hatching in the fall until the first hard frost in the following year. However, in warmer climates and in captivity females of this species may live for several years. Males probably die after mating in their first year.
As is true in many spider species, females of this species grow to much larger size than males. Adult female body length ranges from 19 to 28 mm (3/4 to 1 1/8 in.), while males reach only 5 to 9 mm (1/4 - 3/8 in.). In both sexes, the shiny, egg-shaped abdomen has striking yellow or orange markings on a black background. The forward part of the body, the cephalothorax, is covered with short, silvery hairs. Legs are mostly black, with red or yellow portions near the body.
Like other orb-weavers (family Araneidae), this species has three claws per foot, one more than most spiders. Orb-weavers use this third claw to help handle the threads while spinning. Also in common with other orb-weaving spiders (and most, but not all spiders generally), A. aurantia has a venomous bite that immobilizes prey that is caught in its web.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; venomous
Sexual Dimorphism: female larger
When disturbed, the spider might first vibrate the web to try to make its body look bigger, but if that fails to deter a predator she will drop to the ground and hide (Faulkner 1999). Adults may be captured by wasps such as the Blue Mud Dauber, Chalybion californicum (Landes et al. 1987). They are also eaten by birds, lizards, and shrews.
Overwintering egg cases protect spiderlings from predation. Suspending the cocoon from the web is particularly effective against ant predation. The vast majority, however, are eventually damaged by birds. Cocoons wall layers provide barriers against burrowing larvae of insect predators and ovipositors of parasitic insects, but ichneumonid wasps such as Tromatopia rufopectus and chloropid flies such as Pseudogaurax signatus lay their eggs in Argiope aurantia egg cases. In fact, one study found that in addition to A. aurantia, nineteen species of insects and eleven species of spiders emerged from A. aurantia egg cases. (Hieber 1993, Lockley and Young 1993).
Anti-predator Adaptations: aposematic
Once they mature, males of this species leave their webs and wander in search of females. When they find them, they wait around the edge of her web, sometimes building small webs of their own. We don't have any information on whether males or females mate more than once, or with more than one partner. Probably each female mates with one or more males.
Mating System: polygynandrous (promiscuous)
After mating, each female produces one or more (rarely 4, usually less) brown, papery egg sacs. They are roughly round in shape and up to 25 mm in diameter; each contains 300 to 1400 eggs. She attaches her egg sacs to one side of her web, close to her resting position at the center.
Breeding interval: Once per year
Range number of offspring: 300 to 1400.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Each female watches over her eggs as long as she can, but she will die in the first hard frost, if not before.
Parental Investment: no parental involvement; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
Argiope aurantia is a species of spider, commonly known as the yellow garden spider,[2][3] black and yellow garden spider,[4] golden garden spider,[5] writing spider, zigzag spider, zipper spider, black and yellow argiope, corn spider, Steeler spider, or McKinley spider.[6] The species was first described by Hippolyte Lucas in 1833. It is common to the contiguous United States, Hawaii, southern Canada, Mexico, and Central America. It has distinctive yellow and black markings on the abdomen and a mostly white cephalothorax. Its scientific Latin name translates to "gilded silver-face" (the genus name Argiope meaning "silver-face", while the specific epithet aurantia means "gilded"). The body length of males range from 5–9 mm (0.20–0.35 in); females range from 19–28 mm (0.75–1.10 in). These spiders may bite if disturbed or harassed, but the venom is harmless to non-allergic humans, roughly equivalent to a bumblebee sting in intensity.[7]
Yellow garden spiders often build webs in areas adjacent to open sunny fields where they stay concealed and protected from the wind. The spider can also be found along the eaves of houses and outbuildings or in any tall vegetation where they can securely stretch a web.
Female Argiope aurantia spiders tend to be somewhat local, often staying in one place throughout much of their lifetime.
The web of the yellow garden spider is distinctive: a circular shape up to 2 feet (60 cm) in diameter, with a dense zigzag of silk, known as a stabilimentum, in the center. The purpose of the stabilimentum is disputed. It is possible that it acts as camouflage for the spider lurking in the web's center, but it may also attract insect prey, or even warn birds of the presence of the otherwise difficult-to-see web. Only those spiders that are active during the day construct stabilimenta in their webs.
To construct the web, several radial lines are stretched among four or five anchor points that can be more than three feet apart. The radial lines meet at a central point. The spider makes a frame with several more radial lines and then fills the center with a spiral of silk, leaving a 7.9–9.5 mm (0.31–0.37 in) gap between the spiral rings, starting with the innermost ring and moving outward in a clockwise motion. To ensure that the web is taut, the spider bends the radial lines slightly together while applying the silk spiral. The female builds a substantially larger web than the male's small zigzag web, often found nearby. The spider occupies the center of the web, usually facing straight down, waiting for prey to become ensnared in it. If disturbed by a possible predator, she may drop from the web and hide on the ground nearby. The web normally remains in one location for the entire summer, but spiders can change locations usually early in the season, perhaps to find better protection or better hunting.
The yellow garden spider can oscillate her web vigorously while she remains firmly attached in the center.[8] This action might prevent predators like wasps and birds from drawing a good bead, and also to fully entangle an insect before it cuts itself loose. However, in a case observed in Georgia, Davis witnessed a Vespa crabro fly into the spider's web and get tangled up. Upon looking closer it was found that V. crabro was actually cutting free prey that had been caught in the A. aurantia web. In this case, A. aurantia did not interfere or fight with the European hornet, probably because it dropped from the web and hid nearby.[9]
The yellow garden spider does not live in very dense location clusters like other orb spiders such as the golden orb web spider. The yellow garden spider keeps a clean orderly web in comparison to the cluttered series of webs built and abandoned by groups of golden orb spiders.
This spider is found from Canada to Costa Rica,[1] but less so in the basin and mountain areas of the Rockies.[10]
Argiope spiders are not aggressive. They might bite if grabbed, but other than for defense they do not attack large animals. Their venom often contains a library of polyamine toxins with potential as therapeutic medicinal agents. Notable among these is the argiotoxin ArgTX-636.[11]
A bite by Argiope aurantia is comparable to a bee sting with redness and swelling. For a healthy adult, a bite is not considered an issue. Though these spiders are not aggressive, people who are very young, elderly, or who have compromised immune systems should exercise caution, just as they would around a beehive or a hornet nest.[12][13][14]
Yellow garden spiders breed twice a year. The males roam in search of a female, building a small web near or actually in the female's web, then court the females by plucking strands on her web. Often, when the male approaches the female, he has a safety drop line ready, in case she attacks him. The male uses the palpal bulbs on his pedipalps to transfer sperm to the female. After inserting the second palpal bulb, the male dies, and is sometimes then eaten by the female.[15]
The female lays her eggs at night on a sheet of silky material, then covers them with another layer of silk, then a protective brownish silk. She then uses her legs to form the sheet into a ball with an upturned neck. Egg sacs range from 5/8" to 1" in diameter. The location of the egg sac varies. She sometimes suspends the egg sac near her web or placed several feet from the web. Each spider produces from one to four sacs with perhaps over a thousand eggs inside each.
In the spring, the young spiders exit the sac. They are so tiny that they look like dust gathered inside the silk mesh. Some of the spiderlings remain nearby, but others exude a strand of silk that gets caught by the breeze, carrying the spiderling to a more distant area.[7]
Females of the species are the most commonly seen in gardens. Their webs are usually characterized by a zigzag shaped stabilimentum (an extra thick line of silk) in the middle extending vertically. The spiders spend most of their time in their webs, waiting for prey to become ensnared. When prey becomes caught in the web, the spider may undulate the web back and forth to further trap the insect. When the prey is secure, the spider kills it by injecting its venom and then wraps the prey in a cocoon of silk for later consumption (typically 1–4 hours later). Prey includes small vertebrates, such as geckos and green anoles, as well as insects.[7][16]
Female
Ventral view
Side view
Male
In web, displaying the characteristic zig-zag stabilimentum
Egg sac
Eating a swallowtail butterfly in Holly Springs, North Carolina
Female consuming a moth
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On web
Capturing and wrapping several honey bees
Argiope aurantia is a species of spider, commonly known as the yellow garden spider, black and yellow garden spider, golden garden spider, writing spider, zigzag spider, zipper spider, black and yellow argiope, corn spider, Steeler spider, or McKinley spider. The species was first described by Hippolyte Lucas in 1833. It is common to the contiguous United States, Hawaii, southern Canada, Mexico, and Central America. It has distinctive yellow and black markings on the abdomen and a mostly white cephalothorax. Its scientific Latin name translates to "gilded silver-face" (the genus name Argiope meaning "silver-face", while the specific epithet aurantia means "gilded"). The body length of males range from 5–9 mm (0.20–0.35 in); females range from 19–28 mm (0.75–1.10 in). These spiders may bite if disturbed or harassed, but the venom is harmless to non-allergic humans, roughly equivalent to a bumblebee sting in intensity.
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